Module system

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The compiler depends on the System module to work properly and the System module depends on the compiler. Most of the routines listed here use special compiler magic. Each module implicitly imports the System module; it must not be listed explicitly. Because of this there cannot be a user-defined module named system.

Module system

Types

int
default integer type; bitwidth depends on architecture, but is always the same as a pointer   Source Edit
int8
signed 8 bit integer type   Source Edit
int16
signed 16 bit integer type   Source Edit
int32
signed 32 bit integer type   Source Edit
int64
signed 64 bit integer type   Source Edit
uint
unsigned default integer type   Source Edit
uint8
unsigned 8 bit integer type   Source Edit
uint16
unsigned 16 bit integer type   Source Edit
uint32
unsigned 32 bit integer type   Source Edit
uint64
unsigned 64 bit integer type   Source Edit
float
default floating point type   Source Edit
float32
32 bit floating point type   Source Edit
float64
64 bit floating point type   Source Edit
bool = enum
  false = 0, true = 1
built-in boolean type   Source Edit
char
built-in 8 bit character type (unsigned)   Source Edit
string
built-in string type   Source Edit
cstring
built-in cstring (compatible string) type   Source Edit
pointer
built-in pointer type, use the addr operator to get a pointer to a variable   Source Edit
typedesc
meta type to denote a type description   Source Edit
Ordinal[T]
Generic ordinal type. Includes integer, bool, character, and enumeration types as well as their subtypes. Note uint and uint64 are not ordinal types for implementation reasons   Source Edit
ptr[T]
built-in generic untraced pointer type   Source Edit
ref[T]
built-in generic traced pointer type   Source Edit
expr
meta type to denote an expression (for templates) Deprecated since version 0.15. Use untyped instead.   Source Edit
stmt
meta type to denote a statement (for templates) Deprecated since version 0.15. Use typed instead.   Source Edit
void
meta type to denote the absence of any type   Source Edit
auto
meta type for automatic type determination   Source Edit
any = distinct auto
meta type for any supported type   Source Edit
untyped
meta type to denote an expression that is not resolved (for templates)   Source Edit
typed
meta type to denote an expression that is resolved (for templates)   Source Edit
SomeSignedInt = int | int8 | int16 | int32 | int64
type class matching all signed integer types   Source Edit
SomeUnsignedInt = uint | uint8 | uint16 | uint32 | uint64
type class matching all unsigned integer types   Source Edit
SomeInteger = SomeSignedInt | SomeUnsignedInt
type class matching all integer types   Source Edit
SomeOrdinal = int | int8 | int16 | int32 | int64 | bool | enum | uint8 | uint16 | uint32
type class matching all ordinal types; however this includes enums with holes.   Source Edit
SomeReal = float | float32 | float64
type class matching all floating point number types   Source Edit
SomeNumber = SomeInteger | SomeReal
type class matching all number types   Source Edit
range[T]
Generic type to construct range types.   Source Edit
array[I, T]
Generic type to construct fixed-length arrays.   Source Edit
openArray[T]
Generic type to construct open arrays. Open arrays are implemented as a pointer to the array data and a length field.   Source Edit
varargs[T]
Generic type to construct a varargs type.   Source Edit
seq[T]
Generic type to construct sequences.   Source Edit
set[T]
Generic type to construct bit sets.   Source Edit
Slice[T] = object
  a*, b*: T                     ## the bounds
  
builtin slice type   Source Edit
byte = uint8
this is an alias for uint8, that is an unsigned int 8 bits wide.   Source Edit
Natural = range[0 .. high(int)]
is an int type ranging from zero to the maximum value of an int. This type is often useful for documentation and debugging.   Source Edit
Positive = range[1 .. high(int)]
is an int type ranging from one to the maximum value of an int. This type is often useful for documentation and debugging.   Source Edit
RootObj = object
the root of Nim's object hierarchy. Objects should inherit from RootObj or one of its descendants. However, objects that have no ancestor are allowed.   Source Edit
RootRef = ref RootObj
reference to RootObj   Source Edit
RootEffect = object of RootObj
base effect class; each effect should inherit from TEffect unless you know what you doing.   Source Edit
TimeEffect = object of RootEffect
Time effect.   Source Edit
IOEffect = object of RootEffect
IO effect.   Source Edit
ReadIOEffect = object of IOEffect
Effect describing a read IO operation.   Source Edit
WriteIOEffect = object of IOEffect
Effect describing a write IO operation.   Source Edit
ExecIOEffect = object of IOEffect
Effect describing an executing IO operation.   Source Edit
Exception = object of RootObj
  parent*: ref Exception        ## parent exception (can be used as a stack)
  name*: cstring               ## The exception's name is its Nim identifier.
               ## This field is filled automatically in the
               ## ``raise`` statement.
  msg* {.
exportc: "message"
.}: string ## the exception's message. Not ## providing an exception message ## is bad style. trace: string

Base exception class.

Each exception has to inherit from Exception. See the full exception hierarchy.

  Source Edit
SystemError = object of Exception

Abstract class for exceptions that the runtime system raises.

See the full exception hierarchy.

  Source Edit
IOError = object of SystemError

Raised if an IO error occurred.

See the full exception hierarchy.

  Source Edit
EOFError = object of IOError

Raised if an IO "end of file" error occurred.

See the full exception hierarchy.

  Source Edit
OSError = object of SystemError
  errorCode*: int32            ## OS-defined error code describing this error.
  

Raised if an operating system service failed.

See the full exception hierarchy.

  Source Edit
LibraryError = object of OSError

Raised if a dynamic library could not be loaded.

See the full exception hierarchy.

  Source Edit
ResourceExhaustedError = object of SystemError

Raised if a resource request could not be fulfilled.

See the full exception hierarchy.

  Source Edit
ArithmeticError = object of Exception

Raised if any kind of arithmetic error occurred.

See the full exception hierarchy.

  Source Edit
DivByZeroError = object of ArithmeticError

Raised for runtime integer divide-by-zero errors.

See the full exception hierarchy.

  Source Edit
OverflowError = object of ArithmeticError

Raised for runtime integer overflows.

This happens for calculations whose results are too large to fit in the provided bits. See the full exception hierarchy.

  Source Edit
AccessViolationError = object of Exception

Raised for invalid memory access errors

See the full exception hierarchy.

  Source Edit
AssertionError = object of Exception

Raised when assertion is proved wrong.

Usually the result of using the assert() template. See the full exception hierarchy.

  Source Edit
ValueError = object of Exception
Raised for string and object conversion errors.   Source Edit
KeyError = object of ValueError

Raised if a key cannot be found in a table.

Mostly used by the tables module, it can also be raised by other collection modules like sets or strtabs. See the full exception hierarchy.

  Source Edit
OutOfMemError = object of SystemError

Raised for unsuccessful attempts to allocate memory.

See the full exception hierarchy.

  Source Edit
IndexError = object of Exception

Raised if an array index is out of bounds.

See the full exception hierarchy.

  Source Edit
FieldError = object of Exception

Raised if a record field is not accessible because its dicriminant's value does not fit.

See the full exception hierarchy.

  Source Edit
RangeError = object of Exception

Raised if a range check error occurred.

See the full exception hierarchy.

  Source Edit
StackOverflowError = object of SystemError

Raised if the hardware stack used for subroutine calls overflowed.

See the full exception hierarchy.

  Source Edit
ReraiseError = object of Exception

Raised if there is no exception to reraise.

See the full exception hierarchy.

  Source Edit
ObjectAssignmentError = object of Exception

Raised if an object gets assigned to its parent's object.

See the full exception hierarchy.

  Source Edit
ObjectConversionError = object of Exception

Raised if an object is converted to an incompatible object type. You can use of operator to check if conversion will succeed.

See the full exception hierarchy.

  Source Edit
FloatingPointError = object of Exception

Base class for floating point exceptions.

See the full exception hierarchy.

  Source Edit
FloatInvalidOpError = object of FloatingPointError

Raised by invalid operations according to IEEE.

Raised by 0.0/0.0, for example. See the full exception hierarchy.

  Source Edit
FloatDivByZeroError = object of FloatingPointError

Raised by division by zero.

Divisor is zero and dividend is a finite nonzero number. See the full exception hierarchy.

  Source Edit
FloatOverflowError = object of FloatingPointError

Raised for overflows.

The operation produced a result that exceeds the range of the exponent. See the full exception hierarchy.

  Source Edit
FloatUnderflowError = object of FloatingPointError

Raised for underflows.

The operation produced a result that is too small to be represented as a normal number. See the full exception hierarchy.

  Source Edit
FloatInexactError = object of FloatingPointError

Raised for inexact results.

The operation produced a result that cannot be represented with infinite precision -- for example: 2.0 / 3.0, log(1.1)

NOTE: Nim currently does not detect these! See the full exception hierarchy.

  Source Edit
DeadThreadError = object of Exception

Raised if it is attempted to send a message to a dead thread.

See the full exception hierarchy.

  Source Edit
NilAccessError = object of SystemError

Raised on dereferences of nil pointers.

This is only raised if the segfaults.nim module was imported!

  Source Edit
Endianness = enum
  littleEndian, bigEndian
is a type describing the endianness of a processor.   Source Edit
TaintedString = string
a distinct string type that is tainted, see taint mode for details. It is an alias for string if the taint mode is not turned on.   Source Edit
ByteAddress = int
is the signed integer type that should be used for converting pointers to integer addresses for readability.   Source Edit
BiggestInt = int64
is an alias for the biggest signed integer type the Nim compiler supports. Currently this is int64, but it is platform-dependant in general.   Source Edit
BiggestFloat = float64
is an alias for the biggest floating point type the Nim compiler supports. Currently this is float64, but it is platform-dependant in general.   Source Edit
BiggestUInt = uint64
is an alias for the biggest unsigned integer type the Nim compiler supports. Currently this is uint32 for JS and uint64 for other targets.   Source Edit
clong = int32
This is the same as the type long in C.   Source Edit
culong = uint32
This is the same as the type unsigned long in C.   Source Edit
cchar = char
This is the same as the type char in C.   Source Edit
cschar = int8
This is the same as the type signed char in C.   Source Edit
cshort = int16
This is the same as the type short in C.   Source Edit
cint = int32
This is the same as the type int in C.   Source Edit
csize = int
This is the same as the type size_t in C.   Source Edit
clonglong = int64
This is the same as the type long long in C.   Source Edit
cfloat = float32
This is the same as the type float in C.   Source Edit
cdouble = float64
This is the same as the type double in C.   Source Edit
clongdouble = BiggestFloat
This is the same as the type long double in C. This C type is not supported by Nim's code generator.   Source Edit
cuchar = char
This is the same as the type unsigned char in C.   Source Edit
cushort = uint16
This is the same as the type unsigned short in C.   Source Edit
cuint = uint32
This is the same as the type unsigned int in C.   Source Edit
culonglong = uint64
This is the same as the type unsigned long long in C.   Source Edit
cstringArray = ptr array[0 .. ArrayDummySize, cstring]
This is binary compatible to the type char** in C. The array's high value is large enough to disable bounds checking in practice. Use cstringArrayToSeq to convert it into a seq[string].   Source Edit
PFloat32 = ptr float32
an alias for ptr float32   Source Edit
PFloat64 = ptr float64
an alias for ptr float64   Source Edit
PInt64 = ptr int64
an alias for ptr int64   Source Edit
PInt32 = ptr int32
an alias for ptr int32   Source Edit
GC_Strategy = enum
  gcThroughput,               ## optimize for throughput
  gcResponsiveness,           ## optimize for responsiveness (default)
  gcOptimizeTime,             ## optimize for speed
  gcOptimizeSpace             ## optimize for memory footprint
the strategy the GC should use for the application   Source Edit
PFrame = ptr TFrame
represents a runtime frame of the call stack; part of the debugger API.   Source Edit
TFrame = object
  prev*: PFrame                ## previous frame; used for chaining the call stack
  procname*: cstring           ## name of the proc that is currently executing
  line*: int                   ## line number of the proc that is currently executing
  filename*: cstring           ## filename of the proc that is currently executing
  len*: int16                  ## length of the inspectable slots
  calldepth*: int16            ## used for max call depth checking
  
the frame itself   Source Edit
FileSeekPos = enum
  fspSet,                     ## Seek to absolute value
  fspCur,                     ## Seek relative to current position
  fspEnd                      ## Seek relative to end
Position relative to which seek should happen   Source Edit
File = ptr CFile
The type representing a file handle.   Source Edit
FileMode = enum
  fmRead,                     ## Open the file for read access only.
  fmWrite,                    ## Open the file for write access only.
          ## If the file does not exist, it will be
          ## created.
  fmReadWrite,                ## Open the file for read and write access.
              ## If the file does not exist, it will be
              ## created. Existing files will be cleared!
  fmReadWriteExisting,        ## Open the file for read and write access.
                      ## If the file does not exist, it will not be
                      ## created. The existing file will not be cleared.
  fmAppend                    ## Open the file for writing only; append data
          ## at the end.
The file mode when opening a file.   Source Edit
FileHandle = cint
type that represents an OS file handle; this is useful for low-level file access   Source Edit
ForeignCell = object
  data*: pointer
  owner: ptr GcHeap
  Source Edit
Utf16Char = distinct int16
  Source Edit
WideCString = ref array[0 .. 1000000, Utf16Char]
  Source Edit
NimNode = ref NimNodeObj
represents a Nim AST node. Macros operate on this type.   Source Edit

Vars

programResult: int
modify this variable to specify the exit code of the program under normal circumstances. When the program is terminated prematurely using quit, this value is ignored.   Source Edit
globalRaiseHook: proc (e: ref Exception): bool {.
nimcall, gcsafe, locks: 0
.}
with this hook you can influence exception handling on a global level. If not nil, every 'raise' statement ends up calling this hook. Ordinary application code should never set this hook! You better know what you do when setting this. If globalRaiseHook returns false, the exception is caught and does not propagate further through the call stack.   Source Edit
localRaiseHook: proc (e: ref Exception): bool {.
nimcall, gcsafe, locks: 0
.}
with this hook you can influence exception handling on a thread local level. If not nil, every 'raise' statement ends up calling this hook. Ordinary application code should never set this hook! You better know what you do when setting this. If localRaiseHook returns false, the exception is caught and does not propagate further through the call stack.   Source Edit
outOfMemHook: proc () {.
nimcall, tags: [], gcsafe, locks: 0
.}
set this variable to provide a procedure that should be called in case of an out of memory event. The standard handler writes an error message and terminates the program. outOfMemHook can be used to raise an exception in case of OOM like so:
var gOutOfMem: ref EOutOfMemory
new(gOutOfMem) # need to be allocated *before* OOM really happened!
gOutOfMem.msg = "out of memory"

proc handleOOM() =
  raise gOutOfMem

system.outOfMemHook = handleOOM

If the handler does not raise an exception, ordinary control flow continues and the program is terminated.

  Source Edit
stdin: File
The standard input stream.   Source Edit
stdout: File
The standard output stream.   Source Edit
stderr: File
The standard error stream.   Source Edit
errorMessageWriter: (proc (msg: string) {.
tags: [WriteIOEffect], gcsafe, locks: 0, nimcall
.})
Function that will be called instead of stdmsg.write when printing stacktrace. Unstable API.   Source Edit

Lets

nimvm: bool = false
may be used only in "when" expression. It is true in Nim VM context and false otherwise   Source Edit

Consts

on = true
alias for true   Source Edit
off = false
alias for false   Source Edit
appType: string = ""
a string that describes the application type. Possible values: "console", "gui", "lib".   Source Edit
NoFakeVars = false
true if the backend doesn't support "fake variables" like 'var EBADF {.importc.}: cint'.   Source Edit
isMainModule: bool = false
is true only when accessed in the main module. This works thanks to compiler magic. It is useful to embed testing code in a module.   Source Edit
CompileDate: string = "0000-00-00"
is the date of compilation as a string of the form YYYY-MM-DD. This works thanks to compiler magic.   Source Edit
CompileTime: string = "00:00:00"
is the time of compilation as a string of the form HH:MM:SS. This works thanks to compiler magic.   Source Edit
cpuEndian: Endianness = littleEndian
is the endianness of the target CPU. This is a valuable piece of information for low-level code only. This works thanks to compiler magic.   Source Edit
hostOS: string = ""
a string that describes the host operating system. Possible values: "windows", "macosx", "linux", "netbsd", "freebsd", "openbsd", "solaris", "aix", "standalone".   Source Edit
hostCPU: string = ""
a string that describes the host CPU. Possible values: "i386", "alpha", "powerpc", "powerpc64", "powerpc64el", "sparc", "amd64", "mips", "mipsel", "arm", "arm64".   Source Edit
nimEnableCovariance = false
  Source Edit
QuitSuccess = 0
is the value that should be passed to quit to indicate success.   Source Edit
QuitFailure = 1
is the value that should be passed to quit to indicate failure.   Source Edit
Inf = inf
contains the IEEE floating point value of positive infinity.   Source Edit
NegInf = -inf
contains the IEEE floating point value of negative infinity.   Source Edit
NaN = nan
contains an IEEE floating point value of Not A Number. Note that you cannot compare a floating point value to this value and expect a reasonable result - use the classify procedure in the module math for checking for NaN.   Source Edit
NimMajor: int = 0
is the major number of Nim's version.   Source Edit
NimMinor: int = 17
is the minor number of Nim's version.   Source Edit
NimPatch: int = 0
is the patch number of Nim's version.   Source Edit
NimVersion: string = "0.17.0"
is the version of Nim as a string.   Source Edit
nimCoroutines = false
  Source Edit
nativeStackTraceSupported = false
  Source Edit

Procs

proc `or`(a, b: typedesc): typedesc {.
magic: "TypeTrait", noSideEffect
.}
Constructs an or meta class   Source Edit
proc `and`(a, b: typedesc): typedesc {.
magic: "TypeTrait", noSideEffect
.}
Constructs an and meta class   Source Edit
proc `not`(a: typedesc): typedesc {.
magic: "TypeTrait", noSideEffect
.}
Constructs an not meta class   Source Edit
proc defined(x: untyped): bool {.
magic: "Defined", noSideEffect, compileTime
.}
Special compile-time procedure that checks whether x is defined. x is an external symbol introduced through the compiler's -d:x switch to enable build time conditionals:
when not defined(release):
  # Do here programmer friendly expensive sanity checks.
# Put here the normal code
  Source Edit
proc declared(x: untyped): bool {.
magic: "Defined", noSideEffect, compileTime
.}
Special compile-time procedure that checks whether x is declared. x has to be an identifier or a qualified identifier. This can be used to check whether a library provides a certain feature or not:
when not declared(strutils.toUpper):
  # provide our own toUpper proc here, because strutils is
  # missing it.
  Source Edit
proc definedInScope(x: untyped): bool {.
magic: "DefinedInScope", noSideEffect, deprecated, compileTime
.}
Deprecated since version 0.9.6: Use declaredInScope instead.   Source Edit
proc declaredInScope(x: untyped): bool {.
magic: "DefinedInScope", noSideEffect, compileTime
.}
Special compile-time procedure that checks whether x is declared in the current scope. x has to be an identifier.   Source Edit
proc `addr`[T](x: var T): ptr T {.
magic: "Addr", noSideEffect
.}
Builtin 'addr' operator for taking the address of a memory location. Cannot be overloaded.
var
  buf: seq[char] = @['a','b','c']
  p: pointer = buf[1].addr
echo cast[ptr char](p)[]    # b
  Source Edit
proc unsafeAddr[T](x: T): ptr T {.
magic: "Addr", noSideEffect
.}
Builtin 'addr' operator for taking the address of a memory location. This works even for let variables or parameters for better interop with C and so it is considered even more unsafe than the ordinary addr. When you use it to write a wrapper for a C library, you should always check that the original library does never write to data behind the pointer that is returned from this procedure. Cannot be overloaded.   Source Edit
proc `type`(x: untyped): typedesc {.
magic: "TypeOf", noSideEffect, compileTime
.}
Builtin 'type' operator for accessing the type of an expression. Cannot be overloaded.   Source Edit
proc `not`(x: bool): bool {.
magic: "Not", noSideEffect
.}
Boolean not; returns true iff x == false.   Source Edit
proc `and`(x, y: bool): bool {.
magic: "And", noSideEffect
.}
Boolean and; returns true iff x == y == true. Evaluation is lazy: if x is false, y will not even be evaluated.   Source Edit
proc `or`(x, y: bool): bool {.
magic: "Or", noSideEffect
.}
Boolean or; returns true iff not (not x and not y). Evaluation is lazy: if x is true, y will not even be evaluated.   Source Edit
proc `xor`(x, y: bool): bool {.
magic: "Xor", noSideEffect
.}
Boolean exclusive or; returns true iff x != y.   Source Edit
proc new[T](a: var ref T) {.
magic: "New", noSideEffect
.}
creates a new object of type T and returns a safe (traced) reference to it in a.   Source Edit
proc new(T: typedesc): auto

creates a new object of type T and returns a safe (traced) reference to it as result value.

When T is a ref type then the resulting type will be T, otherwise it will be ref T.

  Source Edit
proc internalNew[T](a: var ref T) {.
magic: "New", noSideEffect
.}
leaked implementation detail. Do not use.   Source Edit
proc new[T](a: var ref T; finalizer: proc (x: ref T) {.
nimcall
.}) {.
magic: "NewFinalize", noSideEffect
.}
creates a new object of type T and returns a safe (traced) reference to it in a. When the garbage collector frees the object, finalizer is called. The finalizer may not keep a reference to the object pointed to by x. The finalizer cannot prevent the GC from freeing the object. Note: The finalizer refers to the type T, not to the object! This means that for each object of type T the finalizer will be called!   Source Edit
proc reset[T](obj: var T) {.
magic: "Reset", noSideEffect
.}
resets an object obj to its initial (binary zero) value. This needs to be called before any possible object branch transition.   Source Edit
proc high[T](x: T): T {.
magic: "High", noSideEffect
.}
returns the highest possible index of an array, a sequence, a string or the highest possible value of an ordinal value x. As a special semantic rule, x may also be a type identifier. high(int) is Nim's way of writing INT_MAX or MAX_INT.
var arr = [1,2,3,4,5,6,7]
high(arr) #=> 6
high(2) #=> 9223372036854775807
high(int) #=> 9223372036854775807
  Source Edit
proc low[T](x: T): T {.
magic: "Low", noSideEffect
.}
returns the lowest possible index of an array, a sequence, a string or the lowest possible value of an ordinal value x. As a special semantic rule, x may also be a type identifier.
var arr = [1,2,3,4,5,6,7]
low(arr) #=> 0
low(2) #=> -9223372036854775808
low(int) #=> -9223372036854775808
  Source Edit
proc `[]`[I: Ordinal, T](a: T; i: I): T {.
noSideEffect, magic: "ArrGet"
.}
  Source Edit
proc `[]=`[I: Ordinal, T, S](a: T; i: I; x: S) {.
noSideEffect, magic: "ArrPut"
.}
  Source Edit
proc `=`[T](dest: var T; src: T) {.
noSideEffect, magic: "Asgn"
.}
  Source Edit
proc `..`[T](a, b: T): Slice[T] {.
noSideEffect, inline, magic: "DotDot"
.}
slice operator that constructs an interval [a, b], both a and b are inclusive. Slices can also be used in the set constructor and in ordinal case statements, but then they are special-cased by the compiler.   Source Edit
proc `..`[T](b: T): Slice[T] {.
noSideEffect, inline, magic: "DotDot"
.}
slice operator that constructs an interval [default(T), b]   Source Edit
proc `==`[Enum: enum](x, y: Enum): bool {.
magic: "EqEnum", noSideEffect
.}
Checks whether values within the same enum have the same underlying value
type
  Enum1 = enum
    Field1 = 3, Field2
  Enum2 = enum
    Place1, Place2 = 3
var
  e1 = Field1
  e2 = Enum1(Place2)
echo (e1 == e2) # true
echo (e1 == Place2) # raises error
  Source Edit
proc `==`(x, y: pointer): bool {.
magic: "EqRef", noSideEffect
.}
var # this is a wildly dangerous example
  a = cast[pointer](0)
  b = cast[pointer](nil)
echo (a == b) # true due to the special meaning of `nil`/0 as a pointer
  Source Edit
proc `==`(x, y: string): bool {.
magic: "EqStr", noSideEffect
.}
Checks for equality between two string variables   Source Edit
proc `==`(x, y: char): bool {.
magic: "EqCh", noSideEffect
.}
Checks for equality between two char variables   Source Edit
proc `==`(x, y: bool): bool {.
magic: "EqB", noSideEffect
.}
Checks for equality between two bool variables   Source Edit
proc `==`[T](x, y: set[T]): bool {.
magic: "EqSet", noSideEffect
.}
Checks for equality between two variables of type set
var a = {1, 2, 2, 3} # duplication in sets is ignored
var b = {1, 2, 3}
echo (a == b) # true
  Source Edit
proc `==`[T](x, y: ref T): bool {.
magic: "EqRef", noSideEffect
.}
Checks that two ref variables refer to the same item   Source Edit
proc `==`[T](x, y: ptr T): bool {.
magic: "EqRef", noSideEffect
.}
Checks that two ptr variables refer to the same item   Source Edit
proc `==`[T: proc](x, y: T): bool {.
magic: "EqProc", noSideEffect
.}
Checks that two proc variables refer to the same procedure   Source Edit
proc `<=`[Enum: enum](x, y: Enum): bool {.
magic: "LeEnum", noSideEffect
.}
  Source Edit
proc `<=`(x, y: string): bool {.
magic: "LeStr", noSideEffect
.}
  Source Edit
proc `<=`(x, y: char): bool {.
magic: "LeCh", noSideEffect
.}
  Source Edit
proc `<=`[T](x, y: set[T]): bool {.
magic: "LeSet", noSideEffect
.}
  Source Edit
proc `<=`(x, y: bool): bool {.
magic: "LeB", noSideEffect
.}
  Source Edit
proc `<=`[T](x, y: ref T): bool {.
magic: "LePtr", noSideEffect
.}
  Source Edit
proc `<=`(x, y: pointer): bool {.
magic: "LePtr", noSideEffect
.}
  Source Edit
proc `<`[Enum: enum](x, y: Enum): bool {.
magic: "LtEnum", noSideEffect
.}
  Source Edit
proc `<`(x, y: string): bool {.
magic: "LtStr", noSideEffect
.}
  Source Edit
proc `<`(x, y: char): bool {.
magic: "LtCh", noSideEffect
.}
  Source Edit
proc `<`[T](x, y: set[T]): bool {.
magic: "LtSet", noSideEffect
.}
  Source Edit
proc `<`(x, y: bool): bool {.
magic: "LtB", noSideEffect
.}
  Source Edit
proc `<`[T](x, y: ref T): bool {.
magic: "LtPtr", noSideEffect
.}
  Source Edit
proc `<`[T](x, y: ptr T): bool {.
magic: "LtPtr", noSideEffect
.}
  Source Edit
proc `<`(x, y: pointer): bool {.
magic: "LtPtr", noSideEffect
.}
  Source Edit
proc unsafeNew[T](a: var ref T; size: Natural) {.
magic: "New", noSideEffect
.}
creates a new object of type T and returns a safe (traced) reference to it in a. This is unsafe as it allocates an object of the passed size. This should only be used for optimization purposes when you know what you're doing!   Source Edit
proc sizeof[T](x: T): int {.
magic: "SizeOf", noSideEffect
.}

returns the size of x in bytes. Since this is a low-level proc, its usage is discouraged - using new for the most cases suffices that one never needs to know x's size. As a special semantic rule, x may also be a type identifier (sizeof(int) is valid).

Limitations: If used within nim VM context sizeof will only work for simple types.

sizeof('A') #=> 1
sizeof(2) #=> 8
  Source Edit
proc sizeof(x: typedesc): int {.
magic: "SizeOf", noSideEffect
.}
  Source Edit
proc `<`[T](x: Ordinal[T]): T {.
magic: "UnaryLt", noSideEffect
.}
unary < that can be used for nice looking excluding ranges:
for i in 0 .. <10: echo i #=> 0 1 2 3 4 5 6 7 8 9

Semantically this is the same as pred.

  Source Edit
proc succ[T](x: Ordinal[T]; y = 1): T {.
magic: "Succ", noSideEffect
.}
returns the y-th successor of the value x. T has to be an ordinal type. If such a value does not exist, EOutOfRange is raised or a compile time error occurs.   Source Edit
proc pred[T](x: Ordinal[T]; y = 1): T {.
magic: "Pred", noSideEffect
.}
returns the y-th predecessor of the value x. T has to be an ordinal type. If such a value does not exist, EOutOfRange is raised or a compile time error occurs.   Source Edit
proc inc[T: Ordinal | uint | uint64](x: var T; y = 1) {.
magic: "Inc", noSideEffect
.}
increments the ordinal x by y. If such a value does not exist, EOutOfRange is raised or a compile time error occurs. This is a short notation for: x = succ(x, y).
var i = 2
inc(i) #=> 3
inc(i, 3) #=> 6
  Source Edit
proc dec[T: Ordinal | uint | uint64](x: var T; y = 1) {.
magic: "Dec", noSideEffect
.}
decrements the ordinal x by y. If such a value does not exist, EOutOfRange is raised or a compile time error occurs. This is a short notation for: x = pred(x, y).
var i = 2
dec(i) #=> 1
dec(i, 3) #=> -2
  Source Edit
proc newSeq[T](s: var seq[T]; len: Natural) {.
magic: "NewSeq", noSideEffect
.}

creates a new sequence of type seq[T] with length len. This is equivalent to s = @[]; setlen(s, len), but more efficient since no reallocation is needed.

Note that the sequence will be filled with zeroed entries, which can be a problem for sequences containing strings since their value will be nil. After the creation of the sequence you should assign entries to the sequence instead of adding them. Example:

var inputStrings : seq[string]
newSeq(inputStrings, 3)
inputStrings[0] = "The fourth"
inputStrings[1] = "assignment"
inputStrings[2] = "would crash"
#inputStrings[3] = "out of bounds"
  Source Edit
proc newSeq[T](len = 0.Natural): seq[T]

creates a new sequence of type seq[T] with length len.

Note that the sequence will be filled with zeroed entries, which can be a problem for sequences containing strings since their value will be nil. After the creation of the sequence you should assign entries to the sequence instead of adding them. Example:

var inputStrings = newSeq[string](3)
inputStrings[0] = "The fourth"
inputStrings[1] = "assignment"
inputStrings[2] = "would crash"
#inputStrings[3] = "out of bounds"
  Source Edit
proc newSeqOfCap[T](cap: Natural): seq[T] {.
magic: "NewSeqOfCap", noSideEffect
.}
creates a new sequence of type seq[T] with length 0 and capacity cap.   Source Edit
proc len[TOpenArray: openArray | varargs](x: TOpenArray): int {.
magic: "LengthOpenArray", noSideEffect
.}
  Source Edit
proc len(x: string): int {.
magic: "LengthStr", noSideEffect
.}
  Source Edit
proc len(x: cstring): int {.
magic: "LengthStr", noSideEffect
.}
  Source Edit
proc len[I, T](x: array[I, T]): int {.
magic: "LengthArray", noSideEffect
.}
  Source Edit
proc len[T](x: seq[T]): int {.
magic: "LengthSeq", noSideEffect
.}
returns the length of an array, an openarray, a sequence or a string. This is roughly the same as high(T)-low(T)+1, but its resulting type is always an int.
var arr = [1,1,1,1,1]
len(arr) #=> 5
for i in 0..<arr.len:
  echo arr[i] #=> 1,1,1,1,1
  Source Edit
proc incl[T](x: var set[T]; y: T) {.
magic: "Incl", noSideEffect
.}
includes element y to the set x. This is the same as x = x + {y}, but it might be more efficient.
var a = initSet[int](4)
a.incl(2) #=> {2}
a.incl(3) #=> {2, 3}
  Source Edit
proc excl[T](x: var set[T]; y: T) {.
magic: "Excl", noSideEffect
.}
excludes element y to the set x. This is the same as x = x - {y}, but it might be more efficient.
var b = {2,3,5,6,12,545}
b.excl(5)  #=> {2,3,6,12,545}
  Source Edit
proc card[T](x: set[T]): int {.
magic: "Card", noSideEffect
.}
returns the cardinality of the set x, i.e. the number of elements in the set.
var i = {1,2,3,4}
card(i) #=> 4
  Source Edit
proc ord[T](x: T): int {.
magic: "Ord", noSideEffect
.}
returns the internal int value of an ordinal value x.
ord('A') #=> 65
  Source Edit
proc chr(u: range[0 .. 255]): char {.
magic: "Chr", noSideEffect
.}
converts an int in the range 0..255 to a character.
chr(65) #=> A
  Source Edit
proc ze(x: int8): int {.
magic: "Ze8ToI", noSideEffect
.}
zero extends a smaller integer type to int. This treats x as unsigned.   Source Edit
proc ze(x: int16): int {.
magic: "Ze16ToI", noSideEffect
.}
zero extends a smaller integer type to int. This treats x as unsigned.   Source Edit
proc ze64(x: int8): int64 {.
magic: "Ze8ToI64", noSideEffect
.}
zero extends a smaller integer type to int64. This treats x as unsigned.   Source Edit
proc ze64(x: int16): int64 {.
magic: "Ze16ToI64", noSideEffect
.}
zero extends a smaller integer type to int64. This treats x as unsigned.   Source Edit
proc ze64(x: int32): int64 {.
magic: "Ze32ToI64", noSideEffect
.}
zero extends a smaller integer type to int64. This treats x as unsigned.   Source Edit
proc ze64(x: int): int64 {.
magic: "ZeIToI64", noSideEffect
.}
zero extends a smaller integer type to int64. This treats x as unsigned. Does nothing if the size of an int is the same as int64. (This is the case on 64 bit processors.)   Source Edit
proc toU8(x: int): int8 {.
magic: "ToU8", noSideEffect
.}
treats x as unsigned and converts it to a byte by taking the last 8 bits from x.   Source Edit
proc toU16(x: int): int16 {.
magic: "ToU16", noSideEffect
.}
treats x as unsigned and converts it to an int16 by taking the last 16 bits from x.   Source Edit
proc toU32(x: int64): int32 {.
magic: "ToU32", noSideEffect
.}
treats x as unsigned and converts it to an int32 by taking the last 32 bits from x.   Source Edit
proc `+`(x: int): int {.
magic: "UnaryPlusI", noSideEffect
.}
  Source Edit
proc `+`(x: int8): int8 {.
magic: "UnaryPlusI", noSideEffect
.}
  Source Edit
proc `+`(x: int16): int16 {.
magic: "UnaryPlusI", noSideEffect
.}
  Source Edit
proc `+`(x: int32): int32 {.
magic: "UnaryPlusI", noSideEffect
.}
  Source Edit
proc `+`(x: int64): int64 {.
magic: "UnaryPlusI", noSideEffect
.}
Unary + operator for an integer. Has no effect.   Source Edit
proc `-`(x: int): int {.
magic: "UnaryMinusI", noSideEffect
.}
  Source Edit
proc `-`(x: int8): int8 {.
magic: "UnaryMinusI", noSideEffect
.}
  Source Edit
proc `-`(x: int16): int16 {.
magic: "UnaryMinusI", noSideEffect
.}
  Source Edit
proc `-`(x: int32): int32 {.
magic: "UnaryMinusI", noSideEffect
.}
  Source Edit
proc `-`(x: int64): int64 {.
magic: "UnaryMinusI64", noSideEffect
.}
Unary - operator for an integer. Negates x.   Source Edit
proc `not`(x: int): int {.
magic: "BitnotI", noSideEffect
.}
  Source Edit
proc `not`(x: int8): int8 {.
magic: "BitnotI", noSideEffect
.}
  Source Edit
proc `not`(x: int16): int16 {.
magic: "BitnotI", noSideEffect
.}
  Source Edit
proc `not`(x: int32): int32 {.
magic: "BitnotI", noSideEffect
.}
computes the bitwise complement of the integer x.   Source Edit
proc `not`(x: int64): int64 {.
magic: "BitnotI", noSideEffect
.}
  Source Edit
proc `+`(x, y: int): int {.
magic: "AddI", noSideEffect
.}
  Source Edit
proc `+`(x, y: int8): int8 {.
magic: "AddI", noSideEffect
.}
  Source Edit
proc `+`(x, y: int16): int16 {.
magic: "AddI", noSideEffect
.}
  Source Edit
proc `+`(x, y: int32): int32 {.
magic: "AddI", noSideEffect
.}
Binary + operator for an integer.   Source Edit
proc `+`(x, y: int64): int64 {.
magic: "AddI", noSideEffect
.}
  Source Edit
proc `-`(x, y: int): int {.
magic: "SubI", noSideEffect
.}
  Source Edit
proc `-`(x, y: int8): int8 {.
magic: "SubI", noSideEffect
.}
  Source Edit
proc `-`(x, y: int16): int16 {.
magic: "SubI", noSideEffect
.}
  Source Edit
proc `-`(x, y: int32): int32 {.
magic: "SubI", noSideEffect
.}
Binary - operator for an integer.   Source Edit
proc `-`(x, y: int64): int64 {.
magic: "SubI", noSideEffect
.}
  Source Edit
proc `*`(x, y: int): int {.
magic: "MulI", noSideEffect
.}
  Source Edit
proc `*`(x, y: int8): int8 {.
magic: "MulI", noSideEffect
.}
  Source Edit
proc `*`(x, y: int16): int16 {.
magic: "MulI", noSideEffect
.}
  Source Edit
proc `*`(x, y: int32): int32 {.
magic: "MulI", noSideEffect
.}
Binary * operator for an integer.   Source Edit
proc `*`(x, y: int64): int64 {.
magic: "MulI", noSideEffect
.}
  Source Edit
proc `div`(x, y: int): int {.
magic: "DivI", noSideEffect
.}
  Source Edit
proc `div`(x, y: int8): int8 {.
magic: "DivI", noSideEffect
.}
  Source Edit
proc `div`(x, y: int16): int16 {.
magic: "DivI", noSideEffect
.}
  Source Edit
proc `div`(x, y: int32): int32 {.
magic: "DivI", noSideEffect
.}
computes the integer division. This is roughly the same as floor(x/y).
1 div 2 == 0
2 div 2 == 1
3 div 2 == 1
7 div 5 == 1
  Source Edit
proc `div`(x, y: int64): int64 {.
magic: "DivI", noSideEffect
.}
  Source Edit
proc `mod`(x, y: int): int {.
magic: "ModI", noSideEffect
.}
  Source Edit
proc `mod`(x, y: int8): int8 {.
magic: "ModI", noSideEffect
.}
  Source Edit
proc `mod`(x, y: int16): int16 {.
magic: "ModI", noSideEffect
.}
  Source Edit
proc `mod`(x, y: int32): int32 {.
magic: "ModI", noSideEffect
.}
computes the integer modulo operation (remainder). This is the same as x - (x div y) * y.
(7 mod 5) == 2
  Source Edit
proc `mod`(x, y: int64): int64 {.
magic: "ModI", noSideEffect
.}
  Source Edit
proc `shr`(x: int; y: SomeInteger): int {.
magic: "ShrI", noSideEffect
.}
  Source Edit
proc `shr`(x: int8; y: SomeInteger): int8 {.
magic: "ShrI", noSideEffect
.}
  Source Edit
proc `shr`(x: int16; y: SomeInteger): int16 {.
magic: "ShrI", noSideEffect
.}
  Source Edit
proc `shr`(x: int32; y: SomeInteger): int32 {.
magic: "ShrI", noSideEffect
.}
  Source Edit
proc `shr`(x: int64; y: SomeInteger): int64 {.
magic: "ShrI", noSideEffect
.}
computes the shift right operation of x and y, filling vacant bit positions with zeros.
0b0001_0000'i8 shr 2 == 0b0000_0100'i8
0b1000_0000'i8 shr 8 == 0b0000_0000'i8
0b0000_0001'i8 shr 1 == 0b0000_0000'i8
  Source Edit
proc `shl`(x: int; y: SomeInteger): int {.
magic: "ShlI", noSideEffect
.}
  Source Edit
proc `shl`(x: int8; y: SomeInteger): int8 {.
magic: "ShlI", noSideEffect
.}
  Source Edit
proc `shl`(x: int16; y: SomeInteger): int16 {.
magic: "ShlI", noSideEffect
.}
  Source Edit
proc `shl`(x: int32; y: SomeInteger): int32 {.
magic: "ShlI", noSideEffect
.}
  Source Edit
proc `shl`(x: int64; y: SomeInteger): int64 {.
magic: "ShlI", noSideEffect
.}
computes the shift left operation of x and y.
1'i32 shl 4 == 0x0000_0010
1'i64 shl 4 == 0x0000_0000_0000_0010
  Source Edit
proc `and`(x, y: int): int {.
magic: "BitandI", noSideEffect
.}
  Source Edit
proc `and`(x, y: int8): int8 {.
magic: "BitandI", noSideEffect
.}
  Source Edit
proc `and`(x, y: int16): int16 {.
magic: "BitandI", noSideEffect
.}
  Source Edit
proc `and`(x, y: int32): int32 {.
magic: "BitandI", noSideEffect
.}
  Source Edit
proc `and`(x, y: int64): int64 {.
magic: "BitandI", noSideEffect
.}
computes the bitwise and of numbers x and y.
(0xffff'i16 and 0x0010'i16) == 0x0010
  Source Edit
proc `or`(x, y: int): int {.
magic: "BitorI", noSideEffect
.}
  Source Edit
proc `or`(x, y: int8): int8 {.
magic: "BitorI", noSideEffect
.}
  Source Edit
proc `or`(x, y: int16): int16 {.
magic: "BitorI", noSideEffect
.}
  Source Edit
proc `or`(x, y: int32): int32 {.
magic: "BitorI", noSideEffect
.}
  Source Edit
proc `or`(x, y: int64): int64 {.
magic: "BitorI", noSideEffect
.}
computes the bitwise or of numbers x and y.
(0x0005'i16 or 0x0010'i16) == 0x0015
  Source Edit
proc `xor`(x, y: int): int {.
magic: "BitxorI", noSideEffect
.}
  Source Edit
proc `xor`(x, y: int8): int8 {.
magic: "BitxorI", noSideEffect
.}
  Source Edit
proc `xor`(x, y: int16): int16 {.
magic: "BitxorI", noSideEffect
.}
  Source Edit
proc `xor`(x, y: int32): int32 {.
magic: "BitxorI", noSideEffect
.}
  Source Edit
proc `xor`(x, y: int64): int64 {.
magic: "BitxorI", noSideEffect
.}
computes the bitwise xor of numbers x and y.
(0x1011'i16 xor 0x0101'i16) == 0x1110
  Source Edit
proc `==`(x, y: int): bool {.
magic: "EqI", noSideEffect
.}
  Source Edit
proc `==`(x, y: int8): bool {.
magic: "EqI", noSideEffect
.}
  Source Edit
proc `==`(x, y: int16): bool {.
magic: "EqI", noSideEffect
.}
  Source Edit
proc `==`(x, y: int32): bool {.
magic: "EqI", noSideEffect
.}
  Source Edit
proc `==`(x, y: int64): bool {.
magic: "EqI", noSideEffect
.}
Compares two integers for equality.   Source Edit
proc `<=`(x, y: int): bool {.
magic: "LeI", noSideEffect
.}
  Source Edit
proc `<=`(x, y: int8): bool {.
magic: "LeI", noSideEffect
.}
  Source Edit
proc `<=`(x, y: int16): bool {.
magic: "LeI", noSideEffect
.}
  Source Edit
proc `<=`(x, y: int32): bool {.
magic: "LeI", noSideEffect
.}
  Source Edit
proc `<=`(x, y: int64): bool {.
magic: "LeI", noSideEffect
.}
Returns true iff x is less than or equal to y.   Source Edit
proc `<`(x, y: int): bool {.
magic: "LtI", noSideEffect
.}
  Source Edit
proc `<`(x, y: int8): bool {.
magic: "LtI", noSideEffect
.}
  Source Edit
proc `<`(x, y: int16): bool {.
magic: "LtI", noSideEffect
.}
  Source Edit
proc `<`(x, y: int32): bool {.
magic: "LtI", noSideEffect
.}
  Source Edit
proc `<`(x, y: int64): bool {.
magic: "LtI", noSideEffect
.}
Returns true iff x is less than y.   Source Edit
proc `+%`(x, y: IntMax32): IntMax32 {.
magic: "AddU", noSideEffect
.}
  Source Edit
proc `+%`(x, y: int64): int64 {.
magic: "AddU", noSideEffect
.}
treats x and y as unsigned and adds them. The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.   Source Edit
proc `-%`(x, y: IntMax32): IntMax32 {.
magic: "SubU", noSideEffect
.}
  Source Edit
proc `-%`(x, y: int64): int64 {.
magic: "SubU", noSideEffect
.}
treats x and y as unsigned and subtracts them. The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.   Source Edit
proc `*%`(x, y: IntMax32): IntMax32 {.
magic: "MulU", noSideEffect
.}
  Source Edit
proc `*%`(x, y: int64): int64 {.
magic: "MulU", noSideEffect
.}
treats x and y as unsigned and multiplies them. The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.   Source Edit
proc `/%`(x, y: IntMax32): IntMax32 {.
magic: "DivU", noSideEffect
.}
  Source Edit
proc `/%`(x, y: int64): int64 {.
magic: "DivU", noSideEffect
.}
treats x and y as unsigned and divides them. The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.   Source Edit
proc `%%`(x, y: IntMax32): IntMax32 {.
magic: "ModU", noSideEffect
.}
  Source Edit
proc `%%`(x, y: int64): int64 {.
magic: "ModU", noSideEffect
.}
treats x and y as unsigned and compute the modulo of x and y. The result is truncated to fit into the result. This implements modulo arithmetic. No overflow errors are possible.   Source Edit
proc `<=%`(x, y: IntMax32): bool {.
magic: "LeU", noSideEffect
.}
  Source Edit
proc `<=%`(x, y: int64): bool {.
magic: "LeU64", noSideEffect
.}
treats x and y as unsigned and compares them. Returns true iff unsigned(x) <= unsigned(y).   Source Edit
proc `<%`(x, y: IntMax32): bool {.
magic: "LtU", noSideEffect
.}
  Source Edit
proc `<%`(x, y: int64): bool {.
magic: "LtU64", noSideEffect
.}
treats x and y as unsigned and compares them. Returns true iff unsigned(x) < unsigned(y).   Source Edit
proc `not`[T: SomeUnsignedInt](x: T): T {.
magic: "BitnotI", noSideEffect
.}
computes the bitwise complement of the integer x.   Source Edit
proc `shr`[T: SomeUnsignedInt](x: T; y: SomeInteger): T {.
magic: "ShrI", noSideEffect
.}
computes the shift right operation of x and y.   Source Edit
proc `shl`[T: SomeUnsignedInt](x: T; y: SomeInteger): T {.
magic: "ShlI", noSideEffect
.}
computes the shift left operation of x and y.   Source Edit
proc `and`[T: SomeUnsignedInt](x, y: T): T {.
magic: "BitandI", noSideEffect
.}
computes the bitwise and of numbers x and y.   Source Edit
proc `or`[T: SomeUnsignedInt](x, y: T): T {.
magic: "BitorI", noSideEffect
.}
computes the bitwise or of numbers x and y.   Source Edit
proc `xor`[T: SomeUnsignedInt](x, y: T): T {.
magic: "BitxorI", noSideEffect
.}
computes the bitwise xor of numbers x and y.   Source Edit
proc `==`[T: SomeUnsignedInt](x, y: T): bool {.
magic: "EqI", noSideEffect
.}
Compares two unsigned integers for equality.   Source Edit
proc `+`[T: SomeUnsignedInt](x, y: T): T {.
magic: "AddU", noSideEffect
.}
Binary + operator for unsigned integers.   Source Edit
proc `-`[T: SomeUnsignedInt](x, y: T): T {.
magic: "SubU", noSideEffect
.}
Binary - operator for unsigned integers.   Source Edit
proc `*`[T: SomeUnsignedInt](x, y: T): T {.
magic: "MulU", noSideEffect
.}
Binary * operator for unsigned integers.   Source Edit
proc `div`[T: SomeUnsignedInt](x, y: T): T {.
magic: "DivU", noSideEffect
.}
computes the integer division. This is roughly the same as floor(x/y).
(7 div 5) == 2
  Source Edit
proc `mod`[T: SomeUnsignedInt](x, y: T): T {.
magic: "ModU", noSideEffect
.}
computes the integer modulo operation (remainder). This is the same as x - (x div y) * y.
(7 mod 5) == 2
  Source Edit
proc `<=`[T: SomeUnsignedInt](x, y: T): bool {.
magic: "LeU", noSideEffect
.}
Returns true iff x <= y.   Source Edit
proc `<`[T: SomeUnsignedInt](x, y: T): bool {.
magic: "LtU", noSideEffect
.}
Returns true iff unsigned(x) < unsigned(y).   Source Edit
proc `+`(x: float32): float32 {.
magic: "UnaryPlusF64", noSideEffect
.}
  Source Edit
proc `-`(x: float32): float32 {.
magic: "UnaryMinusF64", noSideEffect
.}
  Source Edit
proc `+`(x, y: float32): float32 {.
magic: "AddF64", noSideEffect
.}
  Source Edit
proc `-`(x, y: float32): float32 {.
magic: "SubF64", noSideEffect
.}
  Source Edit
proc `*`(x, y: float32): float32 {.
magic: "MulF64", noSideEffect
.}
  Source Edit
proc `/`(x, y: float32): float32 {.
magic: "DivF64", noSideEffect
.}
  Source Edit
proc `+`(x: float): float {.
magic: "UnaryPlusF64", noSideEffect
.}
  Source Edit
proc `-`(x: float): float {.
magic: "UnaryMinusF64", noSideEffect
.}
  Source Edit
proc `+`(x, y: float): float {.
magic: "AddF64", noSideEffect
.}
  Source Edit
proc `-`(x, y: float): float {.
magic: "SubF64", noSideEffect
.}
  Source Edit
proc `*`(x, y: float): float {.
magic: "MulF64", noSideEffect
.}
  Source Edit
proc `/`(x, y: float): float {.
magic: "DivF64", noSideEffect
.}
computes the floating point division   Source Edit
proc `==`(x, y: float32): bool {.
magic: "EqF64", noSideEffect
.}
  Source Edit
proc `<=`(x, y: float32): bool {.
magic: "LeF64", noSideEffect
.}
  Source Edit
proc `<`(x, y: float32): bool {.
magic: "LtF64", noSideEffect
.}
  Source Edit
proc `==`(x, y: float): bool {.
magic: "EqF64", noSideEffect
.}
  Source Edit
proc `<=`(x, y: float): bool {.
magic: "LeF64", noSideEffect
.}
  Source Edit
proc `<`(x, y: float): bool {.
magic: "LtF64", noSideEffect
.}
  Source Edit
proc `*`[T](x, y: set[T]): set[T] {.
magic: "MulSet", noSideEffect
.}
This operator computes the intersection of two sets.   Source Edit
proc `+`[T](x, y: set[T]): set[T] {.
magic: "PlusSet", noSideEffect
.}
This operator computes the union of two sets.   Source Edit
proc `-`[T](x, y: set[T]): set[T] {.
magic: "MinusSet", noSideEffect
.}
This operator computes the difference of two sets.   Source Edit
proc contains[T](x: set[T]; y: T): bool {.
magic: "InSet", noSideEffect
.}
One should overload this proc if one wants to overload the in operator. The parameters are in reverse order! a in b is a template for contains(b, a). This is because the unification algorithm that Nim uses for overload resolution works from left to right. But for the in operator that would be the wrong direction for this piece of code:
var s: set[range['a'..'z']] = {'a'..'c'}
writeLine(stdout, 'b' in s)

If in had been declared as [T](elem: T, s: set[T]) then T would have been bound to char. But s is not compatible to type set[char]! The solution is to bind T to range['a'..'z']. This is achieved by reversing the parameters for contains; in then passes its arguments in reverse order.

  Source Edit
proc contains[T](s: Slice[T]; value: T): bool {.
noSideEffect, inline
.}
Checks if value is within the range of s; returns true iff value >= s.a and value <= s.b
assert((1..3).contains(1) == true)
assert((1..3).contains(2) == true)
assert((1..3).contains(4) == false)
  Source Edit
proc `is`[T, S](x: T; y: S): bool {.
magic: "Is", noSideEffect
.}
Checks if T is of the same type as S
proc test[T](a: T): int =
  when (T is int):
    return a
  else:
    return 0

assert(test[int](3) == 3)
assert(test[string]("xyz") == 0)
  Source Edit
proc `of`[T, S](x: T; y: S): bool {.
magic: "Of", noSideEffect
.}
Checks if x has a type of y
assert(FloatingPointError of Exception)
assert(DivByZeroError of Exception)
  Source Edit
proc cmp[T](x, y: T): int {.
procvar
.}
Generic compare proc. Returns a value < 0 iff x < y, a value > 0 iff x > y and 0 iff x == y. This is useful for writing generic algorithms without performance loss. This generic implementation uses the == and < operators.
import algorithm
echo sorted(@[4,2,6,5,8,7], cmp[int])
  Source Edit
proc `@`[IDX, T](a: array[IDX, T]): seq[T] {.
magic: "ArrToSeq", nosideeffect
.}
turns an array into a sequence. This most often useful for constructing sequences with the array constructor: @[1, 2, 3] has the type seq[int], while [1, 2, 3] has the type array[0..2, int].   Source Edit
proc setLen[T](s: var seq[T]; newlen: Natural) {.
magic: "SetLengthSeq", noSideEffect
.}
sets the length of s to newlen. T may be any sequence type. If the current length is greater than the new length, s will be truncated. s cannot be nil! To initialize a sequence with a size, use newSeq instead.   Source Edit
proc setLen(s: var string; newlen: Natural) {.
magic: "SetLengthStr", noSideEffect
.}
sets the length of s to newlen. If the current length is greater than the new length, s will be truncated. s cannot be nil! To initialize a string with a size, use newString instead.
var myS = "Nim is great!!"
myS.setLen(3)
echo myS, " is fantastic!!"
  Source Edit
proc newString(len: Natural): string {.
magic: "NewString", importc: "mnewString", noSideEffect
.}
returns a new string of length len but with uninitialized content. One needs to fill the string character after character with the index operator s[i]. This procedure exists only for optimization purposes; the same effect can be achieved with the & operator or with add.   Source Edit
proc newStringOfCap(cap: Natural): string {.
magic: "NewStringOfCap", importc: "rawNewString", noSideEffect
.}
returns a new string of length 0 but with capacity cap.This procedure exists only for optimization purposes; the same effect can be achieved with the & operator or with add.   Source Edit
proc `&`(x: string; y: char): string {.
magic: "ConStrStr", noSideEffect, merge
.}
Concatenates x with y
assert("ab" & 'c' == "abc")
  Source Edit
proc `&`(x, y: char): string {.
magic: "ConStrStr", noSideEffect, merge
.}
Concatenates x and y into a string
assert('a' & 'b' == "ab")
  Source Edit
proc `&`(x, y: string): string {.
magic: "ConStrStr", noSideEffect, merge
.}
Concatenates x and y
assert("ab" & "cd" == "abcd")
  Source Edit
proc `&`(x: char; y: string): string {.
magic: "ConStrStr", noSideEffect, merge
.}
Concatenates x with y
assert('a' & "bc" == "abc")
  Source Edit
proc add(x: var string; y: char) {.
magic: "AppendStrCh", noSideEffect
.}
Appends y to x in place
var tmp = ""
tmp.add('a')
tmp.add('b')
assert(tmp == "ab")
  Source Edit
proc add(x: var string; y: string) {.
magic: "AppendStrStr", noSideEffect
.}
Concatenates x and y in place
var tmp = ""
tmp.add("ab")
tmp.add("cd")
assert(tmp == "abcd")
  Source Edit
proc compileOption(option: string): bool {.
magic: "CompileOption", noSideEffect
.}
can be used to determine an on|off compile-time option. Example:
when compileOption("floatchecks"):
  echo "compiled with floating point NaN and Inf checks"
  Source Edit
proc compileOption(option, arg: string): bool {.
magic: "CompileOptionArg", noSideEffect
.}
can be used to determine an enum compile-time option. Example:
when compileOption("opt", "size") and compileOption("gc", "boehm"):
  echo "compiled with optimization for size and uses Boehm's GC"
  Source Edit
proc quit(errorcode: int = QuitSuccess) {.
magic: "Exit", noreturn
.}

Stops the program immediately with an exit code.

Before stopping the program the "quit procedures" are called in the opposite order they were added with addQuitProc. quit never returns and ignores any exception that may have been raised by the quit procedures. It does not call the garbage collector to free all the memory, unless a quit procedure calls GC_fullCollect.

The proc quit(QuitSuccess) is called implicitly when your nim program finishes without incident. A raised unhandled exception is equivalent to calling quit(QuitFailure).

Note that this is a runtime call and using quit inside a macro won't have any compile time effect. If you need to stop the compiler inside a macro, use the error or fatal pragmas.

  Source Edit
proc add[T](x: var seq[T]; y: T) {.
magic: "AppendSeqElem", noSideEffect
.}
  Source Edit
proc add[T](x: var seq[T]; y: openArray[T]) {.
noSideEffect
.}
Generic proc for adding a data item y to a container x. For containers that have an order, add means append. New generic containers should also call their adding proc add for consistency. Generic code becomes much easier to write if the Nim naming scheme is respected.
var s: seq[string] = @["test2","test2"]
s.add("test") #=> @[test2, test2, test]
  Source Edit
proc shallowCopy[T](x: var T; y: T) {.
noSideEffect, magic: "ShallowCopy"
.}
use this instead of = for a shallow copy. The shallow copy only changes the semantics for sequences and strings (and types which contain those). Be careful with the changed semantics though! There is a reason why the default assignment does a deep copy of sequences and strings.   Source Edit
proc del[T](x: var seq[T]; i: Natural) {.
noSideEffect
.}
deletes the item at index i by putting x[high(x)] into position i. This is an O(1) operation.
var i = @[1, 2, 3, 4, 5]
i.del(2) #=> @[1, 2, 5, 4]
  Source Edit
proc delete[T](x: var seq[T]; i: Natural) {.
noSideEffect
.}
deletes the item at index i by moving x[i+1..] by one position. This is an O(n) operation.
var i = @[1, 2, 3, 4, 5]
i.delete(2) #=> @[1, 2, 4, 5]
  Source Edit
proc insert[T](x: var seq[T]; item: T; i = 0.Natural) {.
noSideEffect
.}
inserts item into x at position i.
var i = @[1, 2, 3, 4, 5]
i.insert(2, 4) #=> @[1, 2, 3, 4, 2, 5]
  Source Edit
proc repr[T](x: T): string {.
magic: "Repr", noSideEffect
.}
takes any Nim variable and returns its string representation. It works even for complex data graphs with cycles. This is a great debugging tool.
var s: seq[string] = @["test2", "test2"]
var i = @[1, 2, 3, 4, 5]
repr(s) #=> 0x1055eb050[0x1055ec050"test2", 0x1055ec078"test2"]
repr(i) #=> 0x1055ed050[1, 2, 3, 4, 5]
  Source Edit
proc toFloat(i: int): float {.
magic: "ToFloat", noSideEffect, importc: "toFloat"
.}
converts an integer i into a float. If the conversion fails, EInvalidValue is raised. However, on most platforms the conversion cannot fail.   Source Edit
proc toBiggestFloat(i: BiggestInt): BiggestFloat {.
magic: "ToBiggestFloat", noSideEffect, importc: "toBiggestFloat"
.}
converts an biggestint i into a biggestfloat. If the conversion fails, EInvalidValue is raised. However, on most platforms the conversion cannot fail.   Source Edit
proc toInt(f: float): int {.
magic: "ToInt", noSideEffect, importc: "toInt"
.}
converts a floating point number f into an int. Conversion rounds f if it does not contain an integer value. If the conversion fails (because f is infinite for example), EInvalidValue is raised.   Source Edit
proc toBiggestInt(f: BiggestFloat): BiggestInt {.
magic: "ToBiggestInt", noSideEffect, importc: "toBiggestInt"
.}
converts a biggestfloat f into a biggestint. Conversion rounds f if it does not contain an integer value. If the conversion fails (because f is infinite for example), EInvalidValue is raised.   Source Edit
proc addQuitProc(QuitProc: proc () {.
noconv
.}) {.
importc: "atexit", header: "<stdlib.h>"
.}

Adds/registers a quit procedure.

Each call to addQuitProc registers another quit procedure. Up to 30 procedures can be registered. They are executed on a last-in, first-out basis (that is, the last function registered is the first to be executed). addQuitProc raises an EOutOfIndex exception if QuitProc cannot be registered.

  Source Edit
proc copy(s: string; first = 0): string {.
magic: "CopyStr", importc: "copyStr", noSideEffect, deprecated
.}
  Source Edit
proc copy(s: string; first, last: int): string {.
magic: "CopyStrLast", importc: "copyStrLast", noSideEffect, deprecated
.}
copies a slice of s into a new string and returns this new string. The bounds first and last denote the indices of the first and last characters that shall be copied. If last is omitted, it is treated as high(s). Deprecated since version 0.8.12: Use substr instead.   Source Edit
proc substr(s: string; first = 0): string {.
magic: "CopyStr", importc: "copyStr", noSideEffect
.}
  Source Edit
proc substr(s: string; first, last: int): string {.
magic: "CopyStrLast", importc: "copyStrLast", noSideEffect
.}
copies a slice of s into a new string and returns this new string. The bounds first and last denote the indices of the first and last characters that shall be copied. If last is omitted, it is treated as high(s). If last >= s.len, s.len is used instead: This means substr can also be used to cut or limit a string's length.   Source Edit
proc createU(T: typedesc; size = 1.Positive): ptr T:type {.
inline, gcsafe, locks: 0
.}
allocates a new memory block with at least T.sizeof * size bytes. The block has to be freed with resize(block, 0) or free(block). The block is not initialized, so reading from it before writing to it is undefined behaviour! The allocated memory belongs to its allocating thread! Use createSharedU to allocate from a shared heap.   Source Edit
proc create(T: typedesc; size = 1.Positive): ptr T:type {.
inline, gcsafe, locks: 0
.}
allocates a new memory block with at least T.sizeof * size bytes. The block has to be freed with resize(block, 0) or free(block). The block is initialized with all bytes containing zero, so it is somewhat safer than createU. The allocated memory belongs to its allocating thread! Use createShared to allocate from a shared heap.   Source Edit
proc resize[T](p: ptr T; newSize: Natural): ptr T {.
inline, gcsafe, locks: 0
.}
grows or shrinks a given memory block. If p is nil then a new memory block is returned. In either way the block has at least T.sizeof * newSize bytes. If newSize == 0 and p is not nil resize calls free(p). In other cases the block has to be freed with free. The allocated memory belongs to its allocating thread! Use resizeShared to reallocate from a shared heap.   Source Edit
proc createSharedU(T: typedesc; size = 1.Positive): ptr T:type {.
inline, gcsafe, locks: 0
.}
allocates a new memory block on the shared heap with at least T.sizeof * size bytes. The block has to be freed with resizeShared(block, 0) or freeShared(block). The block is not initialized, so reading from it before writing to it is undefined behaviour!   Source Edit
proc createShared(T: typedesc; size = 1.Positive): ptr T:type {.
inline
.}
allocates a new memory block on the shared heap with at least T.sizeof * size bytes. The block has to be freed with resizeShared(block, 0) or freeShared(block). The block is initialized with all bytes containing zero, so it is somewhat safer than createSharedU.   Source Edit
proc resizeShared[T](p: ptr T; newSize: Natural): ptr T {.
inline
.}
grows or shrinks a given memory block on the heap. If p is nil then a new memory block is returned. In either way the block has at least T.sizeof * newSize bytes. If newSize == 0 and p is not nil resizeShared calls freeShared(p). In other cases the block has to be freed with freeShared.   Source Edit
proc freeShared[T](p: ptr T) {.
inline, gcsafe, locks: 0
.}
frees the memory allocated with createShared, createSharedU or resizeShared. This procedure is dangerous! If one forgets to free the memory a leak occurs; if one tries to access freed memory (or just freeing it twice!) a core dump may happen or other memory may be corrupted.   Source Edit
proc swap[T](a, b: var T) {.
magic: "Swap", noSideEffect
.}
swaps the values a and b. This is often more efficient than tmp = a; a = b; b = tmp. Particularly useful for sorting algorithms.   Source Edit
proc `$`(x: int): string {.
magic: "IntToStr", noSideEffect
.}
The stringify operator for an integer argument. Returns x converted to a decimal string. $ is Nim's general way of spelling toString.   Source Edit
proc `$`(x: int64): string {.
magic: "Int64ToStr", noSideEffect
.}
The stringify operator for an integer argument. Returns x converted to a decimal string.   Source Edit
proc `$`(x: float): string {.
magic: "FloatToStr", noSideEffect
.}
The stringify operator for a float argument. Returns x converted to a decimal string.   Source Edit
proc `$`(x: bool): string {.
magic: "BoolToStr", noSideEffect
.}
The stringify operator for a boolean argument. Returns x converted to the string "false" or "true".   Source Edit
proc `$`(x: char): string {.
magic: "CharToStr", noSideEffect
.}
The stringify operator for a character argument. Returns x converted to a string.   Source Edit
proc `$`(x: cstring): string {.
magic: "CStrToStr", noSideEffect
.}
The stringify operator for a CString argument. Returns x converted to a string.   Source Edit
proc `$`(x: string): string {.
magic: "StrToStr", noSideEffect
.}
The stringify operator for a string argument. Returns x as it is. This operator is useful for generic code, so that $expr also works if expr is already a string.   Source Edit
proc `$`[Enum: enum](x: Enum): string {.
magic: "EnumToStr", noSideEffect
.}
The stringify operator for an enumeration argument. This works for any enumeration type thanks to compiler magic. If a $ operator for a concrete enumeration is provided, this is used instead. (In other words: Overwriting is possible.)   Source Edit
proc getRefcount[T](x: ref T): int {.
importc: "getRefcount", noSideEffect
.}
  Source Edit
proc getRefcount(x: string): int {.
importc: "getRefcount", noSideEffect
.}
  Source Edit
proc getRefcount[T](x: seq[T]): int {.
importc: "getRefcount", noSideEffect
.}
retrieves the reference count of an heap-allocated object. The value is implementation-dependent.   Source Edit
proc min(x, y: int): int {.
magic: "MinI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc min(x, y: int8): int8 {.
magic: "MinI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc min(x, y: int16): int16 {.
magic: "MinI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc min(x, y: int32): int32 {.
magic: "MinI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc min(x, y: int64): int64 {.
magic: "MinI", noSideEffect, raises: [], tags: []
.}
The minimum value of two integers.   Source Edit
proc min[T](x: openArray[T]): T
The minimum value of x. T needs to have a < operator.   Source Edit
proc max(x, y: int): int {.
magic: "MaxI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc max(x, y: int8): int8 {.
magic: "MaxI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc max(x, y: int16): int16 {.
magic: "MaxI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc max(x, y: int32): int32 {.
magic: "MaxI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc max(x, y: int64): int64 {.
magic: "MaxI", noSideEffect, raises: [], tags: []
.}
The maximum value of two integers.   Source Edit
proc max[T](x: openArray[T]): T
The maximum value of x. T needs to have a < operator.   Source Edit
proc abs(x: float): float {.
magic: "AbsF64", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc min(x, y: float): float {.
magic: "MinF64", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc max(x, y: float): float {.
magic: "MaxF64", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc min[T](x, y: T): T
  Source Edit
proc max[T](x, y: T): T
  Source Edit
proc clamp[T](x, a, b: T): T
limits the value x within the interval [a, b]
assert((1.4).clamp(0.0, 1.0) == 1.0)
assert((0.5).clamp(0.0, 1.0) == 0.5)
  Source Edit
proc isNil[T](x: seq[T]): bool {.
noSideEffect, magic: "IsNil"
.}
  Source Edit
proc isNil[T](x: ref T): bool {.
noSideEffect, magic: "IsNil"
.}
  Source Edit
proc isNil(x: string): bool {.
noSideEffect, magic: "IsNil"
.}
  Source Edit
proc isNil[T](x: ptr T): bool {.
noSideEffect, magic: "IsNil"
.}
  Source Edit
proc isNil(x: pointer): bool {.
noSideEffect, magic: "IsNil"
.}
  Source Edit
proc isNil(x: cstring): bool {.
noSideEffect, magic: "IsNil"
.}
  Source Edit
proc isNil[T: proc](x: T): bool {.
noSideEffect, magic: "IsNil"
.}
Fast check whether x is nil. This is sometimes more efficient than == nil.   Source Edit
proc `==`[I, T](x, y: array[I, T]): bool
  Source Edit
proc `@`[T](a: openArray[T]): seq[T]
turns an openarray into a sequence. This is not as efficient as turning a fixed length array into a sequence as it always copies every element of a.   Source Edit
proc `&`[T](x, y: seq[T]): seq[T] {.
noSideEffect
.}
Concatenates two sequences. Requires copying of the sequences.
assert(@[1, 2, 3, 4] & @[5, 6] == @[1, 2, 3, 4, 5, 6])
  Source Edit
proc `&`[T](x: seq[T]; y: T): seq[T] {.
noSideEffect
.}
Appends element y to the end of the sequence. Requires copying of the sequence
assert(@[1, 2, 3] & 4 == @[1, 2, 3, 4])
  Source Edit
proc `&`[T](x: T; y: seq[T]): seq[T] {.
noSideEffect
.}
Prepends the element x to the beginning of the sequence. Requires copying of the sequence
assert(1 & @[2, 3, 4] == @[1, 2, 3, 4])
  Source Edit
proc `==`[T](x, y: seq[T]): bool {.
noSideEffect
.}
Generic equals operator for sequences: relies on a equals operator for the element type T.   Source Edit
proc find[T, S](a: T; item: S): int {.
inline
.}
Returns the first index of item in a or -1 if not found. This requires appropriate items and == operations to work.   Source Edit
proc contains[T](a: openArray[T]; item: T): bool {.
inline
.}
Returns true if item is in a or false if not found. This is a shortcut for find(a, item) >= 0.   Source Edit
proc pop[T](s: var seq[T]): T {.
inline, noSideEffect
.}
returns the last item of s and decreases s.len by one. This treats s as a stack and implements the common pop operation.   Source Edit
proc `==`[T: tuple |
    object](x, y: T): bool
generic == operator for tuples that is lifted from the components of x and y.   Source Edit
proc `<=`[T: tuple](x, y: T): bool
generic <= operator for tuples that is lifted from the components of x and y. This implementation uses cmp.   Source Edit
proc `<`[T: tuple](x, y: T): bool
generic < operator for tuples that is lifted from the components of x and y. This implementation uses cmp.   Source Edit
proc `$`[T: tuple |
    object](x: T): string
generic $ operator for tuples that is lifted from the components of x. Example:
$(23, 45) == "(23, 45)"
$() == "()"
  Source Edit
proc `$`[T](x: set[T]): string
generic $ operator for sets that is lifted from the components of x. Example:
${23, 45} == "{23, 45}"
  Source Edit
proc `$`[T](x: seq[T]): string
generic $ operator for seqs that is lifted from the components of x. Example:
$(@[23, 45]) == "@[23, 45]"
  Source Edit
proc GC_ref[T](x: ref T) {.
magic: "GCref", gcsafe, locks: 0
.}
  Source Edit
proc GC_ref[T](x: seq[T]) {.
magic: "GCref", gcsafe, locks: 0
.}
  Source Edit
proc GC_ref(x: string) {.
magic: "GCref", gcsafe, locks: 0
.}
marks the object x as referenced, so that it will not be freed until it is unmarked via GC_unref. If called n-times for the same object x, n calls to GC_unref are needed to unmark x.   Source Edit
proc GC_unref[T](x: ref T) {.
magic: "GCunref", gcsafe, locks: 0
.}
  Source Edit
proc GC_unref[T](x: seq[T]) {.
magic: "GCunref", gcsafe, locks: 0
.}
  Source Edit
proc GC_unref(x: string) {.
magic: "GCunref", gcsafe, locks: 0
.}
see the documentation of GC_ref.   Source Edit
proc add(x: var string; y: cstring) {.
raises: [], tags: []
.}
  Source Edit
proc echo(x: varargs[typed, `$`]) {.
magic: "Echo", tags: [WriteIOEffect], gcsafe, locks: 0, sideEffect
.}

Writes and flushes the parameters to the standard output.

Special built-in that takes a variable number of arguments. Each argument is converted to a string via $, so it works for user-defined types that have an overloaded $ operator. It is roughly equivalent to writeLine(stdout, x); flushFile(stdout), but available for the JavaScript target too.

Unlike other IO operations this is guaranteed to be thread-safe as echo is very often used for debugging convenience. If you want to use echo inside a proc without side effects you can use debugEcho instead.

  Source Edit
proc debugEcho(x: varargs[typed, `$`]) {.
magic: "Echo", noSideEffect, tags: [], raises: []
.}
Same as echo, but as a special semantic rule, debugEcho pretends to be free of side effects, so that it can be used for debugging routines marked as noSideEffect.   Source Edit
proc getTypeInfo[T](x: T): pointer {.
magic: "GetTypeInfo", gcsafe, locks: 0
.}
get type information for x. Ordinary code should not use this, but the typeinfo module instead.   Source Edit
proc abs(x: int): int {.
magic: "AbsI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc abs(x: int8): int8 {.
magic: "AbsI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc abs(x: int16): int16 {.
magic: "AbsI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc abs(x: int32): int32 {.
magic: "AbsI", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc abs(x: int64): int64 {.
magic: "AbsI", noSideEffect, raises: [], tags: []
.}
returns the absolute value of x. If x is low(x) (that is -MININT for its type), an overflow exception is thrown (if overflow checking is turned on).   Source Edit
proc cmp(x, y: string): int {.
noSideEffect, procvar, raises: [], tags: []
.}
Compare proc for strings. More efficient than the generic version.   Source Edit
proc open(f: var File; filename: string; mode: FileMode = fmRead; bufSize: int = - 1): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}

Opens a file named filename with given mode.

Default mode is readonly. Returns true iff the file could be opened. This throws no exception if the file could not be opened.

  Source Edit
proc open(f: var File; filehandle: FileHandle; mode: FileMode = fmRead): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}

Creates a File from a filehandle with given mode.

Default mode is readonly. Returns true iff the file could be opened.

  Source Edit
proc open(filename: string; mode: FileMode = fmRead; bufSize: int = - 1): File {.
raises: [Exception, IOError], tags: []
.}

Opens a file named filename with given mode.

Default mode is readonly. Raises an IO exception if the file could not be opened.

  Source Edit
proc reopen(f: File; filename: string; mode: FileMode = fmRead): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}

reopens the file f with given filename and mode. This is often used to redirect the stdin, stdout or stderr file variables.

Default mode is readonly. Returns true iff the file could be reopened.

  Source Edit
proc setStdIoUnbuffered() {.
tags: [], gcsafe, locks: 0, raises: []
.}
Configures stdin, stdout and stderr to be unbuffered.   Source Edit
proc close(f: File) {.
tags: [], gcsafe, raises: []
.}
Closes the file.   Source Edit
proc endOfFile(f: File): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}
Returns true iff f is at the end.   Source Edit
proc readChar(f: File): char {.
tags: [ReadIOEffect], deprecated, raises: [IOError, EOFError]
.}
Reads a single character from the stream f. Deprecated since version 0.16.2. Use some variant of readBuffer instead.   Source Edit
proc flushFile(f: File) {.
tags: [WriteIOEffect], raises: []
.}
Flushes f's buffer.   Source Edit
proc readAll(file: File): TaintedString {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}

Reads all data from the stream file.

Raises an IO exception in case of an error. It is an error if the current file position is not at the beginning of the file.

  Source Edit
proc readFile(filename: string): TaintedString {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}

Opens a file named filename for reading.

Then calls readAll and closes the file afterwards. Returns the string. Raises an IO exception in case of an error. If you need to call this inside a compile time macro you can use staticRead.

  Source Edit
proc writeFile(filename, content: string) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
Opens a file named filename for writing. Then writes the content completely to the file and closes the file afterwards. Raises an IO exception in case of an error.   Source Edit
proc write(f: File; r: float32) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; i: int) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; i: BiggestInt) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; r: BiggestFloat) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; s: string) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; b: bool) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; c: char) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: []
.}
  Source Edit
proc write(f: File; c: cstring) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; a: varargs[string, `$`]) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
Writes a value to the file f. May throw an IO exception.   Source Edit
proc readLine(f: File): TaintedString {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError, EOFError]
.}
reads a line of text from the file f. May throw an IO exception. A line of text may be delimited by LF or CRLF. The newline character(s) are not part of the returned string.   Source Edit
proc readLine(f: File; line: var TaintedString): bool {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
reads a line of text from the file f into line. line must not be nil! May throw an IO exception. A line of text may be delimited by LF or CRLF. The newline character(s) are not part of the returned string. Returns false if the end of the file has been reached, true otherwise. If false is returned line contains no new data.   Source Edit
proc writeLn[Ty](f: File; x: varargs[Ty, `$`]) {.
inline, tags: [WriteIOEffect], gcsafe, locks: 0, deprecated
.}
Deprecated since version 0.11.4: Use writeLine instead.   Source Edit
proc writeLine[Ty](f: File; x: varargs[Ty, `$`]) {.
inline, tags: [WriteIOEffect], gcsafe, locks: 0
.}
writes the values x to f and then writes "\n". May throw an IO exception.   Source Edit
proc getFileSize(f: File): int64 {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
retrieves the file size (in bytes) of f.   Source Edit
proc readBytes(f: File; a: var openArray[int8 | uint8]; start, len: Natural): int {.
tags: [ReadIOEffect], gcsafe, locks: 0
.}
reads len bytes into the buffer a starting at a[start]. Returns the actual number of bytes that have been read which may be less than len (if not as many bytes are remaining), but not greater.   Source Edit
proc readChars(f: File; a: var openArray[char]; start, len: Natural): int {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}

reads len bytes into the buffer a starting at a[start]. Returns the actual number of bytes that have been read which may be less than len (if not as many bytes are remaining), but not greater.

Warning: The buffer a must be pre-allocated. This can be done using, for example, newString.

  Source Edit
proc readBuffer(f: File; buffer: pointer; len: Natural): int {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
reads len bytes into the buffer pointed to by buffer. Returns the actual number of bytes that have been read which may be less than len (if not as many bytes are remaining), but not greater.   Source Edit
proc writeBytes(f: File; a: openArray[int8 | uint8]; start, len: Natural): int {.
tags: [WriteIOEffect], gcsafe, locks: 0
.}
writes the bytes of a[start..start+len-1] to the file f. Returns the number of actual written bytes, which may be less than len in case of an error.   Source Edit
proc writeChars(f: File; a: openArray[char]; start, len: Natural): int {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
writes the bytes of a[start..start+len-1] to the file f. Returns the number of actual written bytes, which may be less than len in case of an error.   Source Edit
proc writeBuffer(f: File; buffer: pointer; len: Natural): int {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
writes the bytes of buffer pointed to by the parameter buffer to the file f. Returns the number of actual written bytes, which may be less than len in case of an error.   Source Edit
proc setFilePos(f: File; pos: int64; relativeTo: FileSeekPos = fspSet) {.
gcsafe, locks: 0, raises: [IOError], tags: []
.}
sets the position of the file pointer that is used for read/write operations. The file's first byte has the index zero.   Source Edit
proc getFilePos(f: File): int64 {.
gcsafe, locks: 0, raises: [IOError], tags: []
.}
retrieves the current position of the file pointer that is used to read from the file f. The file's first byte has the index zero.   Source Edit
proc getFileHandle(f: File): FileHandle {.
raises: [], tags: []
.}
returns the OS file handle of the file f. This is only useful for platform specific programming.   Source Edit
proc cstringArrayToSeq(a: cstringArray; len: Natural): seq[string] {.
raises: [], tags: []
.}
converts a cstringArray to a seq[string]. a is supposed to be of length len.   Source Edit
proc cstringArrayToSeq(a: cstringArray): seq[string] {.
raises: [], tags: []
.}
converts a cstringArray to a seq[string]. a is supposed to be terminated by nil.   Source Edit
proc allocCStringArray(a: openArray[string]): cstringArray {.
raises: [Exception], tags: []
.}
creates a NULL terminated cstringArray from a. The result has to be freed with deallocCStringArray after it's not needed anymore.   Source Edit
proc deallocCStringArray(a: cstringArray) {.
raises: [Exception], tags: []
.}
frees a NULL terminated cstringArray.   Source Edit
proc atomicInc(memLoc: var int; x: int = 1): int {.
inline, discardable, gcsafe, locks: 0, raises: [], tags: []
.}
atomic increment of memLoc. Returns the value after the operation.   Source Edit
proc atomicDec(memLoc: var int; x: int = 1): int {.
inline, discardable, gcsafe, locks: 0, raises: [], tags: []
.}
atomic decrement of memLoc. Returns the value after the operation.   Source Edit
proc addAndFetch(p: ptr int; val: int): int {.
inline, raises: [], tags: []
.}
  Source Edit
proc atomicInc(memLoc: var int; x: int = 1): int {.
inline, discardable, gcsafe, locks: 0, raises: [], tags: []
.}
atomic increment of memLoc. Returns the value after the operation.   Source Edit
proc atomicDec(memLoc: var int; x: int = 1): int {.
inline, discardable, gcsafe, locks: 0, raises: [], tags: []
.}
atomic decrement of memLoc. Returns the value after the operation.   Source Edit
proc cas[T: bool | int | ptr](p: ptr T; oldValue, newValue: T): bool {.
importc: "__sync_bool_compare_and_swap", nodecl
.}
  Source Edit
proc cpuRelax() {.
inline, raises: [], tags: []
.}
  Source Edit
proc setControlCHook(hook: proc () {.
noconv
.} not nil) {.
raises: [Exception], tags: [RootEffect]
.}
allows you to override the behaviour of your application when CTRL+C is pressed. Only one such hook is supported.   Source Edit
proc writeStackTrace() {.
tags: [WriteIOEffect], gcsafe, raises: [Exception]
.}
writes the current stack trace to stderr. This is only works for debug builds.   Source Edit
proc getStackTrace(): string {.
gcsafe, raises: [], tags: []
.}
gets the current stack trace. This only works for debug builds.   Source Edit
proc getStackTrace(e: ref Exception): string {.
gcsafe, raises: [], tags: []
.}
gets the stack trace associated with e, which is the stack that lead to the raise statement. This only works for debug builds.   Source Edit
proc zeroMem(p: pointer; size: Natural) {.
inline, gcsafe, locks: 0, raises: [], tags: []
.}
overwrites the contents of the memory at p with the value 0. Exactly size bytes will be overwritten. Like any procedure dealing with raw memory this is unsafe.   Source Edit
proc copyMem(dest, source: pointer; size: Natural) {.
inline, gcsafe, locks: 0, tags: [], locks: 0, raises: []
.}
copies the contents from the memory at source to the memory at dest. Exactly size bytes will be copied. The memory regions may not overlap. Like any procedure dealing with raw memory this is unsafe.   Source Edit
proc moveMem(dest, source: pointer; size: Natural) {.
inline, gcsafe, locks: 0, tags: [], locks: 0, raises: []
.}
copies the contents from the memory at source to the memory at dest. Exactly size bytes will be copied. The memory regions may overlap, moveMem handles this case appropriately and is thus somewhat more safe than copyMem. Like any procedure dealing with raw memory this is still unsafe, though.   Source Edit
proc equalMem(a, b: pointer; size: Natural): bool {.
inline, noSideEffect, tags: [], locks: 0, raises: []
.}
compares the memory blocks a and b. size bytes will be compared. If the blocks are equal, true is returned, false otherwise. Like any procedure dealing with raw memory this is unsafe.   Source Edit
proc getFrameState(): FrameState {.
compilerproc, inline, raises: [], tags: []
.}
  Source Edit
proc setFrameState(state: FrameState) {.
compilerproc, inline, raises: [], tags: []
.}
  Source Edit
proc getFrame(): PFrame {.
compilerproc, inline, raises: [], tags: []
.}
  Source Edit
proc setFrame(s: PFrame) {.
compilerproc, inline, raises: [], tags: []
.}
  Source Edit
proc stackTraceAvailable(): bool {.
raises: [], tags: []
.}
  Source Edit
proc stackTraceAvailable(): bool {.
raises: [], tags: []
.}
  Source Edit
proc writeStackTrace() {.
tags: [WriteIOEffect], gcsafe, raises: [Exception]
.}
writes the current stack trace to stderr. This is only works for debug builds.   Source Edit
proc getStackTrace(): string {.
gcsafe, raises: [], tags: []
.}
gets the current stack trace. This only works for debug builds.   Source Edit
proc getStackTrace(e: ref Exception): string {.
gcsafe, raises: [], tags: []
.}
gets the stack trace associated with e, which is the stack that lead to the raise statement. This only works for debug builds.   Source Edit
proc setControlCHook(hook: proc () {.
noconv
.} not nil) {.
raises: [Exception], tags: [RootEffect]
.}
allows you to override the behaviour of your application when CTRL+C is pressed. Only one such hook is supported.   Source Edit
proc iterToProc(iter: typed; envType: typedesc; procName: untyped) {.
magic: "Plugin", compileTime
.}
  Source Edit
proc alloc(size: Natural): pointer {.
noconv, gcsafe, tags: [], gcsafe, locks: 0, raises: [Exception]
.}
allocates a new memory block with at least size bytes. The block has to be freed with realloc(block, 0) or dealloc(block). The block is not initialized, so reading from it before writing to it is undefined behaviour! The allocated memory belongs to its allocating thread! Use allocShared to allocate from a shared heap.   Source Edit
proc alloc0(size: Natural): pointer {.
noconv, gcsafe, tags: [], gcsafe, locks: 0, raises: [Exception]
.}
allocates a new memory block with at least size bytes. The block has to be freed with realloc(block, 0) or dealloc(block). The block is initialized with all bytes containing zero, so it is somewhat safer than alloc. The allocated memory belongs to its allocating thread! Use allocShared0 to allocate from a shared heap.   Source Edit
proc dealloc(p: pointer) {.
noconv, gcsafe, tags: [], gcsafe, locks: 0, raises: [Exception]
.}
frees the memory allocated with alloc, alloc0 or realloc. This procedure is dangerous! If one forgets to free the memory a leak occurs; if one tries to access freed memory (or just freeing it twice!) a core dump may happen or other memory may be corrupted. The freed memory must belong to its allocating thread! Use deallocShared to deallocate from a shared heap.   Source Edit
proc realloc(p: pointer; newSize: Natural): pointer {.
noconv, gcsafe, tags: [], gcsafe, locks: 0, raises: [Exception]
.}
grows or shrinks a given memory block. If p is nil then a new memory block is returned. In either way the block has at least newSize bytes. If newSize == 0 and p is not nil realloc calls dealloc(p). In other cases the block has to be freed with dealloc. The allocated memory belongs to its allocating thread! Use reallocShared to reallocate from a shared heap.   Source Edit
proc getFreeMem(): int {.
gcsafe, raises: [], tags: []
.}
returns the number of bytes that are owned by the process, but do not hold any meaningful data.   Source Edit
proc getTotalMem(): int {.
gcsafe, raises: [], tags: []
.}
returns the number of bytes that are owned by the process.   Source Edit
proc getOccupiedMem(): int {.
gcsafe, raises: [], tags: []
.}
returns the number of bytes that are owned by the process and hold data.   Source Edit
proc getMaxMem(): int {.
raises: [], tags: []
.}
  Source Edit
proc allocShared(size: Natural): pointer {.
noconv, gcsafe, gcsafe, locks: 0, raises: [Exception], tags: []
.}
allocates a new memory block on the shared heap with at least size bytes. The block has to be freed with reallocShared(block, 0) or deallocShared(block). The block is not initialized, so reading from it before writing to it is undefined behaviour!   Source Edit
proc allocShared0(size: Natural): pointer {.
noconv, gcsafe, gcsafe, locks: 0, raises: [Exception], tags: []
.}
allocates a new memory block on the shared heap with at least size bytes. The block has to be freed with reallocShared(block, 0) or deallocShared(block). The block is initialized with all bytes containing zero, so it is somewhat safer than allocShared.   Source Edit
proc deallocShared(p: pointer) {.
noconv, gcsafe, gcsafe, locks: 0, raises: [Exception], tags: []
.}
frees the memory allocated with allocShared, allocShared0 or reallocShared. This procedure is dangerous! If one forgets to free the memory a leak occurs; if one tries to access freed memory (or just freeing it twice!) a core dump may happen or other memory may be corrupted.   Source Edit
proc reallocShared(p: pointer; newSize: Natural): pointer {.
noconv, gcsafe, gcsafe, locks: 0, raises: [Exception], tags: []
.}
grows or shrinks a given memory block on the heap. If p is nil then a new memory block is returned. In either way the block has at least newSize bytes. If newSize == 0 and p is not nil reallocShared calls deallocShared(p). In other cases the block has to be freed with deallocShared.   Source Edit
proc protect(x: pointer): ForeignCell {.
raises: [Exception], tags: []
.}
  Source Edit
proc dispose(x: ForeignCell) {.
raises: [Exception], tags: []
.}
  Source Edit
proc isNotForeign(x: ForeignCell): bool {.
raises: [], tags: []
.}
returns true if 'x' belongs to the calling thread. No deep copy has to be performed then.   Source Edit
proc GC_addCycleRoot[T](p: ref T) {.
inline
.}
adds 'p' to the cycle candidate set for the cycle collector. It is necessary if you used the 'acyclic' pragma for optimization purposes and need to break cycles manually.   Source Edit
proc gcInvariant() {.
raises: [], tags: []
.}
  Source Edit
proc GC_disable() {.
gcsafe, inline, gcsafe, locks: 0, raises: [], tags: []
.}
disables the GC. If called n-times, n calls to GC_enable are needed to reactivate the GC. Note that in most circumstances one should only disable the mark and sweep phase with GC_disableMarkAndSweep.   Source Edit
proc GC_enable() {.
gcsafe, inline, gcsafe, locks: 0, raises: [], tags: []
.}
enables the GC again.   Source Edit
proc GC_setStrategy(strategy: GC_Strategy) {.
gcsafe, deprecated, gcsafe, locks: 0, raises: [], tags: []
.}
tells the GC the desired strategy for the application. Deprecated since version 0.8.14. This has always been a nop.   Source Edit
proc GC_enableMarkAndSweep() {.
gcsafe, gcsafe, locks: 0, raises: [], tags: []
.}
  Source Edit
proc GC_disableMarkAndSweep() {.
gcsafe, gcsafe, locks: 0, raises: [], tags: []
.}
the current implementation uses a reference counting garbage collector with a seldomly run mark and sweep phase to free cycles. The mark and sweep phase may take a long time and is not needed if the application does not create cycles. Thus the mark and sweep phase can be deactivated and activated separately from the rest of the GC.   Source Edit
proc GC_fullCollect() {.
gcsafe, gcsafe, locks: 0, raises: [Exception], tags: [RootEffect]
.}
forces a full garbage collection pass. Ordinary code does not need to call this (and should not).   Source Edit
proc GC_getStatistics(): string {.
gcsafe, gcsafe, locks: 0, raises: [], tags: []
.}
returns an informative string about the GC's activity. This may be useful for tweaking.   Source Edit
proc add(result: var string; x: int64) {.
raises: [], tags: []
.}
  Source Edit
proc add(result: var string; x: float) {.
raises: [], tags: []
.}
  Source Edit
proc readBuffer(f: File; buffer: pointer; len: Natural): int {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
reads len bytes into the buffer pointed to by buffer. Returns the actual number of bytes that have been read which may be less than len (if not as many bytes are remaining), but not greater.   Source Edit
proc readBytes(f: File; a: var openArray[int8 | uint8]; start, len: Natural): int {.
tags: [ReadIOEffect], gcsafe, locks: 0
.}
reads len bytes into the buffer a starting at a[start]. Returns the actual number of bytes that have been read which may be less than len (if not as many bytes are remaining), but not greater.   Source Edit
proc readChars(f: File; a: var openArray[char]; start, len: Natural): int {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}

reads len bytes into the buffer a starting at a[start]. Returns the actual number of bytes that have been read which may be less than len (if not as many bytes are remaining), but not greater.

Warning: The buffer a must be pre-allocated. This can be done using, for example, newString.

  Source Edit
proc write(f: File; c: cstring) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc writeBuffer(f: File; buffer: pointer; len: Natural): int {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
writes the bytes of buffer pointed to by the parameter buffer to the file f. Returns the number of actual written bytes, which may be less than len in case of an error.   Source Edit
proc writeBytes(f: File; a: openArray[int8 | uint8]; start, len: Natural): int {.
tags: [WriteIOEffect], gcsafe, locks: 0
.}
writes the bytes of a[start..start+len-1] to the file f. Returns the number of actual written bytes, which may be less than len in case of an error.   Source Edit
proc writeChars(f: File; a: openArray[char]; start, len: Natural): int {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
writes the bytes of a[start..start+len-1] to the file f. Returns the number of actual written bytes, which may be less than len in case of an error.   Source Edit
proc write(f: File; s: string) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc close(f: File) {.
tags: [], gcsafe, raises: []
.}
Closes the file.   Source Edit
proc readChar(f: File): char {.
tags: [ReadIOEffect], deprecated, raises: [IOError, EOFError]
.}
Reads a single character from the stream f. Deprecated since version 0.16.2. Use some variant of readBuffer instead.   Source Edit
proc flushFile(f: File) {.
tags: [WriteIOEffect], raises: []
.}
Flushes f's buffer.   Source Edit
proc getFileHandle(f: File): FileHandle {.
raises: [], tags: []
.}
returns the OS file handle of the file f. This is only useful for platform specific programming.   Source Edit
proc readLine(f: File; line: var TaintedString): bool {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
reads a line of text from the file f into line. line must not be nil! May throw an IO exception. A line of text may be delimited by LF or CRLF. The newline character(s) are not part of the returned string. Returns false if the end of the file has been reached, true otherwise. If false is returned line contains no new data.   Source Edit
proc readLine(f: File): TaintedString {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError, EOFError]
.}
reads a line of text from the file f. May throw an IO exception. A line of text may be delimited by LF or CRLF. The newline character(s) are not part of the returned string.   Source Edit
proc write(f: File; i: int) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; i: BiggestInt) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; b: bool) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; r: float32) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; r: BiggestFloat) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
  Source Edit
proc write(f: File; c: char) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: []
.}
  Source Edit
proc write(f: File; a: varargs[string, `$`]) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
Writes a value to the file f. May throw an IO exception.   Source Edit
proc endOfFile(f: File): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}
Returns true iff f is at the end.   Source Edit
proc readAll(file: File): TaintedString {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}

Reads all data from the stream file.

Raises an IO exception in case of an error. It is an error if the current file position is not at the beginning of the file.

  Source Edit
proc writeLn[Ty](f: File; x: varargs[Ty, `$`]) {.
inline, tags: [WriteIOEffect], gcsafe, locks: 0, deprecated
.}
Deprecated since version 0.11.4: Use writeLine instead.   Source Edit
proc writeLine[Ty](f: File; x: varargs[Ty, `$`]) {.
inline, tags: [WriteIOEffect], gcsafe, locks: 0
.}
writes the values x to f and then writes "\n". May throw an IO exception.   Source Edit
proc len(w: WideCString): int {.
raises: [], tags: []
.}
returns the length of a widestring. This traverses the whole string to find the binary zero end marker!   Source Edit
proc newWideCString(source: cstring; L: int): WideCString {.
raises: [], tags: []
.}
Returns the unicode character s[i] in result. If doInc == true i is incremented by the number of bytes that have been processed.   Source Edit
proc newWideCString(s: cstring): WideCString {.
raises: [], tags: []
.}
  Source Edit
proc newWideCString(s: string): WideCString {.
raises: [], tags: []
.}
  Source Edit
proc `$`(w: WideCString; estimate: int; replacement: int = 0x0000FFFD): string {.
raises: [], tags: []
.}
  Source Edit
proc `$`(s: WideCString): string {.
raises: [], tags: []
.}
  Source Edit
proc open(f: var File; filename: string; mode: FileMode = fmRead; bufSize: int = - 1): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}

Opens a file named filename with given mode.

Default mode is readonly. Returns true iff the file could be opened. This throws no exception if the file could not be opened.

  Source Edit
proc reopen(f: File; filename: string; mode: FileMode = fmRead): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}

reopens the file f with given filename and mode. This is often used to redirect the stdin, stdout or stderr file variables.

Default mode is readonly. Returns true iff the file could be reopened.

  Source Edit
proc open(f: var File; filehandle: FileHandle; mode: FileMode = fmRead): bool {.
tags: [], gcsafe, locks: 0, raises: []
.}

Creates a File from a filehandle with given mode.

Default mode is readonly. Returns true iff the file could be opened.

  Source Edit
proc setFilePos(f: File; pos: int64; relativeTo: FileSeekPos = fspSet) {.
gcsafe, locks: 0, raises: [IOError], tags: []
.}
sets the position of the file pointer that is used for read/write operations. The file's first byte has the index zero.   Source Edit
proc getFilePos(f: File): int64 {.
gcsafe, locks: 0, raises: [IOError], tags: []
.}
retrieves the current position of the file pointer that is used to read from the file f. The file's first byte has the index zero.   Source Edit
proc getFileSize(f: File): int64 {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
retrieves the file size (in bytes) of f.   Source Edit
proc readFile(filename: string): TaintedString {.
tags: [ReadIOEffect], gcsafe, locks: 0, raises: [IOError]
.}

Opens a file named filename for reading.

Then calls readAll and closes the file afterwards. Returns the string. Raises an IO exception in case of an error. If you need to call this inside a compile time macro you can use staticRead.

  Source Edit
proc writeFile(filename, content: string) {.
tags: [WriteIOEffect], gcsafe, locks: 0, raises: [IOError]
.}
Opens a file named filename for writing. Then writes the content completely to the file and closes the file afterwards. Raises an IO exception in case of an error.   Source Edit
proc setStdIoUnbuffered() {.
tags: [], gcsafe, locks: 0, raises: []
.}
Configures stdin, stdout and stderr to be unbuffered.   Source Edit
proc `$`(x: uint64): string {.
noSideEffect, raises: [], tags: []
.}
The stringify operator for an unsigned integer argument. Returns x converted to a decimal string.   Source Edit
proc getCurrentException(): ref Exception {.
compilerproc, inline, gcsafe, locks: 0, raises: [], tags: []
.}
retrieves the current exception; if there is none, nil is returned.   Source Edit
proc getCurrentExceptionMsg(): string {.
inline, gcsafe, locks: 0, raises: [], tags: []
.}
retrieves the error message that was attached to the current exception; if there is none, "" is returned.   Source Edit
proc onRaise(action: proc (e: ref Exception): bool {.
closure
.}) {.
raises: [], tags: []
.}
can be used in a try statement to setup a Lisp-like condition system: This prevents the 'raise' statement to raise an exception but instead calls action. If action returns false, the exception has been handled and does not propagate further through the call stack.   Source Edit
proc setCurrentException(exc: ref Exception) {.
inline, gcsafe, locks: 0, raises: [], tags: []
.}

sets the current exception.

Warning: Only use this if you know what you are doing.

  Source Edit
proc rawProc[T: proc](x: T): pointer {.
noSideEffect, inline
.}
retrieves the raw proc pointer of the closure x. This is useful for interfacing closures with C.   Source Edit
proc rawEnv[T: proc](x: T): pointer {.
noSideEffect, inline
.}
retrieves the raw environment pointer of the closure x. This is useful for interfacing closures with C.   Source Edit
proc finished[T: proc](x: T): bool {.
noSideEffect, inline
.}
can be used to determine if a first class iterator has finished.   Source Edit
proc quit(errormsg: string; errorcode = QuitFailure) {.
noReturn, raises: [], tags: []
.}
a shorthand for echo(errormsg); quit(errorcode).   Source Edit
proc `/`(x, y: int): float {.
inline, noSideEffect, raises: [], tags: []
.}
integer division that results in a float.   Source Edit
proc `[]`(s: string; x: Slice[int]): string {.
inline, raises: [], tags: []
.}
slice operation for strings.   Source Edit
proc `[]=`(s: var string; x: Slice[int]; b: string) {.
raises: [], tags: []
.}
slice assignment for strings. If b.len is not exactly the number of elements that are referred to by x, a splice is performed:
var s = "abcdef"
s[1 .. ^2] = "xyz"
assert s == "axyzf"
  Source Edit
proc `[]`[Idx, T](a: array[Idx, T]; x: Slice[int]): seq[T]
slice operation for arrays.   Source Edit
proc `[]=`[Idx, T](a: var array[Idx, T]; x: Slice[int]; b: openArray[T])
slice assignment for arrays.   Source Edit
proc `[]`[Idx, T](a: array[Idx, T]; x: Slice[Idx]): seq[T]
slice operation for arrays.   Source Edit
proc `[]=`[Idx, T](a: var array[Idx, T]; x: Slice[Idx]; b: openArray[T])
slice assignment for arrays.   Source Edit
proc `[]`[T](s: seq[T]; x: Slice[int]): seq[T]
slice operation for sequences.   Source Edit
proc `[]=`[T](s: var seq[T]; x: Slice[int]; b: openArray[T])
slice assignment for sequences. If b.len is not exactly the number of elements that are referred to by x, a splice is performed.   Source Edit
proc slurp(filename: string): string {.
magic: "Slurp"
.}
This is an alias for staticRead.   Source Edit
proc staticRead(filename: string): string {.
magic: "Slurp"
.}
Compile-time readFile proc for easy resource embedding:
const myResource = staticRead"mydatafile.bin"

slurp is an alias for staticRead.

  Source Edit
proc gorge(command: string; input = ""; cache = ""): string {.
magic: "StaticExec", raises: [], tags: []
.}
This is an alias for staticExec.   Source Edit
proc staticExec(command: string; input = ""; cache = ""): string {.
magic: "StaticExec", raises: [], tags: []
.}
Executes an external process at compile-time. if input is not an empty string, it will be passed as a standard input to the executed program.
const buildInfo = "Revision " & staticExec("git rev-parse HEAD") &
                  "\nCompiled on " & staticExec("uname -v")

gorge is an alias for staticExec. Note that you can use this proc inside a pragma like passC or passL.

If cache is not empty, the results of staticExec are cached within the nimcache directory. Use --forceBuild to get rid of this caching behaviour then. command & input & cache (the concatenated string) is used to determine whether the entry in the cache is still valid. You can use versioning information for cache:

const stateMachine = staticExec("dfaoptimizer", "input", "0.8.0")
  Source Edit
proc gorgeEx(command: string; input = ""; cache = ""): tuple[output: string, exitCode: int] {.
raises: [], tags: []
.}
Same as gorge but also returns the precious exit code.   Source Edit
proc `+=`[T: SomeOrdinal | uint | uint64](x: var T; y: T) {.
magic: "Inc", noSideEffect
.}
Increments an ordinal   Source Edit
proc `-=`[T: SomeOrdinal | uint | uint64](x: var T; y: T) {.
magic: "Dec", noSideEffect
.}
Decrements an ordinal   Source Edit
proc `*=`[T: SomeOrdinal | uint | uint64](x: var T; y: T) {.
inline, noSideEffect
.}
Binary *= operator for ordinals   Source Edit
proc `+=`[T: float | float32 | float64](x: var T; y: T) {.
inline, noSideEffect
.}
Increments in placee a floating point number   Source Edit
proc `-=`[T: float | float32 | float64](x: var T; y: T) {.
inline, noSideEffect
.}
Decrements in place a floating point number   Source Edit
proc `*=`[T: float | float32 | float64](x: var T; y: T) {.
inline, noSideEffect
.}
Multiplies in place a floating point number   Source Edit
proc `/=`(x: var float64; y: float64) {.
inline, noSideEffect, raises: [], tags: []
.}
Divides in place a floating point number   Source Edit
proc `/=`[T: float | float32](x: var T; y: T) {.
inline, noSideEffect
.}
Divides in place a floating point number   Source Edit
proc `&=`(x: var string; y: string) {.
magic: "AppendStrStr", noSideEffect
.}
  Source Edit
proc astToStr[T](x: T): string {.
magic: "AstToStr", noSideEffect
.}
converts the AST of x into a string representation. This is very useful for debugging.   Source Edit
proc instantiationInfo(index = - 1; fullPaths = false): tuple[filename: string, line: int] {.
magic: "InstantiationInfo", noSideEffect
.}

provides access to the compiler's instantiation stack line information of a template.

While similar to the caller info of other languages, it is determined at compile time.

This proc is mostly useful for meta programming (eg. assert template) to retrieve information about the current filename and line number. Example:

import strutils

template testException(exception, code: expr): stmt =
  try:
    let pos = instantiationInfo()
    discard(code)
    echo "Test failure at $1:$2 with '$3'" % [pos.filename,
      $pos.line, astToStr(code)]
    assert false, "A test expecting failure succeeded?"
  except exception:
    discard

proc tester(pos: int): int =
  let
    a = @[1, 2, 3]
  result = a[pos]

when isMainModule:
  testException(IndexError, tester(30))
  testException(IndexError, tester(1))
  # --> Test failure at example.nim:20 with 'tester(1)'
  Source Edit
proc raiseAssert(msg: string) {.
noinline, raises: [AssertionError], tags: []
.}
  Source Edit
proc failedAssertImpl(msg: string) {.
raises: [], tags: []
.}
  Source Edit
proc shallow[T](s: var seq[T]) {.
noSideEffect, inline
.}
marks a sequence s as shallow. Subsequent assignments will not perform deep copies of s. This is only useful for optimization purposes.   Source Edit
proc shallow(s: var string) {.
noSideEffect, inline, raises: [], tags: []
.}
marks a string s as shallow. Subsequent assignments will not perform deep copies of s. This is only useful for optimization purposes.   Source Edit
proc insert(x: var string; item: string; i = 0.Natural) {.
noSideEffect, raises: [], tags: []
.}
inserts item into x at position i.   Source Edit
proc compiles(x: untyped): bool {.
magic: "Compiles", noSideEffect, compileTime, raises: [], tags: []
.}
Special compile-time procedure that checks whether x can be compiled without any semantic error. This can be used to check whether a type supports some operation:
when compiles(3 + 4):
  echo "'+' for integers is available"
  Source Edit
proc safeAdd[T](x: var seq[T]; y: T) {.
noSideEffect
.}
Adds y to x unless x is not yet initialized; in that case, x becomes @[y]   Source Edit
proc safeAdd(x: var string; y: char) {.
raises: [], tags: []
.}
Adds y to x. If x is nil it is initialized to ""   Source Edit
proc safeAdd(x: var string; y: string) {.
raises: [], tags: []
.}
Adds y to x unless x is not yet initalized; in that case, x becomes y   Source Edit
proc locals(): RootObj {.
magic: "Plugin", noSideEffect, raises: [], tags: []
.}
generates a tuple constructor expression listing all the local variables in the current scope. This is quite fast as it does not rely on any debug or runtime information. Note that in constrast to what the official signature says, the return type is not RootObj but a tuple of a structure that depends on the current scope. Example:
proc testLocals() =
  var
    a = "something"
    b = 4
    c = locals()
    d = "super!"
  
  b = 1
  for name, value in fieldPairs(c):
    echo "name ", name, " with value ", value
  echo "B is ", b
# -> name a with value something
# -> name b with value 4
# -> B is 1
  Source Edit
proc deepCopy[T](x: var T; y: T) {.
noSideEffect, magic: "DeepCopy"
.}
performs a deep copy of x. This is also used by the code generator for the implementation of spawn.   Source Edit
proc procCall(x: untyped) {.
magic: "ProcCall", compileTime, raises: [], tags: []
.}
special magic to prohibit dynamic binding for method calls. This is similar to super in ordinary OO languages.
# 'someMethod' will be resolved fully statically:
procCall someMethod(a, b)
  Source Edit
proc `^`[T](x: int; y: openArray[T]): int {.
noSideEffect, magic: "Roof"
.}
  Source Edit
proc `^`(x: int): int {.
noSideEffect, magic: "Roof", raises: [], tags: []
.}
builtin roof operator that can be used for convenient array access. a[^x] is rewritten to a[a.len-x]. However currently the a expression must not have side effects for this to compile. Note that since this is a builtin, it automatically works for all kinds of overloaded [] or []= accessors.   Source Edit
proc xlen(x: string): int {.
magic: "XLenStr", noSideEffect, raises: [], tags: []
.}
  Source Edit
proc xlen[T](x: seq[T]): int {.
magic: "XLenSeq", noSideEffect
.}
returns the length of a sequence or a string without testing for 'nil'. This is an optimization that rarely makes sense.   Source Edit
proc `==`(x, y: cstring): bool {.
magic: "EqCString", noSideEffect, inline, raises: [], tags: []
.}
Checks for equality between two cstring variables.   Source Edit

Iterators

iterator countdown[T](a, b: T; step = 1): T {.
inline
.}
Counts from ordinal value a down to b (inclusive) with the given step count. T may be any ordinal type, step may only be positive. Note: This fails to count to low(int) if T = int for efficiency reasons.   Source Edit
iterator countup[S, T](a: S; b: T; step = 1): T {.
inline
.}
Counts from ordinal value a up to b (inclusive) with the given step count. S, T may be any ordinal type, step may only be positive. Note: This fails to count to high(int) if T = int for efficiency reasons.   Source Edit
iterator `..`[S, T](a: S; b: T): T {.
inline
.}
An alias for countup.   Source Edit
iterator `||`[S, T](a: S; b: T; annotation = ""): T {.
inline, magic: "OmpParFor", sideEffect
.}
parallel loop iterator. Same as .. but the loop may run in parallel. annotation is an additional annotation for the code generator to use. Note that the compiler maps that to the #pragma omp parallel for construct of OpenMP and as such isn't aware of the parallelism in your code! Be careful! Later versions of || will get proper support by Nim's code generator and GC.   Source Edit
iterator items[T](a: openArray[T]): T {.
inline
.}
iterates over each item of a.   Source Edit
iterator mitems[T](a: var openArray[T]): var T {.
inline
.}
iterates over each item of a so that you can modify the yielded value.   Source Edit
iterator items[IX, T](a: array[IX, T]): T {.
inline
.}
iterates over each item of a.   Source Edit
iterator mitems[IX, T](a: var array[IX, T]): var T {.
inline
.}
iterates over each item of a so that you can modify the yielded value.   Source Edit
iterator items[T](a: set[T]): T {.
inline
.}
iterates over each element of a. items iterates only over the elements that are really in the set (and not over the ones the set is able to hold).   Source Edit
iterator items(a: cstring): char {.
inline, raises: [], tags: []
.}
iterates over each item of a.   Source Edit
iterator mitems(a: var cstring): var char {.
inline, raises: [], tags: []
.}
iterates over each item of a so that you can modify the yielded value.   Source Edit
iterator items(E: typedesc[enum]): E:type
iterates over the values of the enum E.   Source Edit
iterator items[T](s: Slice[T]): T
iterates over the slice s, yielding each value between s.a and s.b (inclusively).   Source Edit
iterator pairs[T](a: openArray[T]): tuple[key: int, val: T] {.
inline
.}
iterates over each item of a. Yields (index, a[index]) pairs.   Source Edit
iterator mpairs[T](a: var openArray[T]): tuple[key: int, val: var T] {.
inline
.}
iterates over each item of a. Yields (index, a[index]) pairs. a[index] can be modified.   Source Edit
iterator pairs[IX, T](a: array[IX, T]): tuple[key: IX, val: T] {.
inline
.}
iterates over each item of a. Yields (index, a[index]) pairs.   Source Edit
iterator mpairs[IX, T](a: var array[IX, T]): tuple[key: IX, val: var T] {.
inline
.}
iterates over each item of a. Yields (index, a[index]) pairs. a[index] can be modified.   Source Edit
iterator pairs[T](a: seq[T]): tuple[key: int, val: T] {.
inline
.}
iterates over each item of a. Yields (index, a[index]) pairs.   Source Edit
iterator mpairs[T](a: var seq[T]): tuple[key: int, val: var T] {.
inline
.}
iterates over each item of a. Yields (index, a[index]) pairs. a[index] can be modified.   Source Edit
iterator pairs(a: string): tuple[key: int, val: char] {.
inline, raises: [], tags: []
.}
iterates over each item of a. Yields (index, a[index]) pairs.   Source Edit
iterator mpairs(a: var string): tuple[key: int, val: var char] {.
inline, raises: [], tags: []
.}
iterates over each item of a. Yields (index, a[index]) pairs. a[index] can be modified.   Source Edit
iterator pairs(a: cstring): tuple[key: int, val: char] {.
inline, raises: [], tags: []
.}
iterates over each item of a. Yields (index, a[index]) pairs.   Source Edit
iterator mpairs(a: var cstring): tuple[key: int, val: var char] {.
inline, raises: [], tags: []
.}
iterates over each item of a. Yields (index, a[index]) pairs. a[index] can be modified.   Source Edit
iterator fields[T: tuple |
    object](x: T): RootObj {.
magic: "Fields", noSideEffect
.}
iterates over every field of x. Warning: This really transforms the 'for' and unrolls the loop. The current implementation also has a bug that affects symbol binding in the loop body.   Source Edit
iterator fields[S: tuple |
    object, T: tuple |
    object](x: S; y: T): tuple[a, b: untyped] {.
magic: "Fields", noSideEffect
.}
iterates over every field of x and y. Warning: This is really transforms the 'for' and unrolls the loop. The current implementation also has a bug that affects symbol binding in the loop body.   Source Edit
iterator fieldPairs[T: tuple |
    object](x: T): RootObj {.
magic: "FieldPairs", noSideEffect
.}

Iterates over every field of x returning their name and value.

When you iterate over objects with different field types you have to use the compile time when instead of a runtime if to select the code you want to run for each type. To perform the comparison use the is operator. Example:

type
  Custom = object
    foo: string
    bar: bool

proc `$`(x: Custom): string =
  result = "Custom:"
  for name, value in x.fieldPairs:
    when value is bool:
      result.add("\n\t" & name & " is " & $value)
    else:
      if value.isNil:
        result.add("\n\t" & name & " (nil)")
      else:
        result.add("\n\t" & name & " '" & value & "'")

Another way to do the same without when is to leave the task of picking the appropriate code to a secondary proc which you overload for each field type and pass the value to.

Warning: This really transforms the 'for' and unrolls the loop. The current implementation also has a bug that affects symbol binding in the loop body.

  Source Edit
iterator fieldPairs[S: tuple |
    object, T: tuple |
    object](x: S; y: T): tuple[a, b: untyped] {.
magic: "FieldPairs", noSideEffect
.}
iterates over every field of x and y. Warning: This really transforms the 'for' and unrolls the loop. The current implementation also has a bug that affects symbol binding in the loop body.   Source Edit
iterator lines(filename: string): TaintedString {.
tags: [ReadIOEffect], raises: [Exception, IOError, IOError]
.}

Iterates over any line in the file named filename.

If the file does not exist EIO is raised. The trailing newline character(s) are removed from the iterated lines. Example:

import strutils

proc transformLetters(filename: string) =
  var buffer = ""
  for line in filename.lines:
    buffer.add(line.replace("a", "0") & '\x0A')
  writeFile(filename, buffer)
  Source Edit
iterator lines(f: File): TaintedString {.
tags: [ReadIOEffect], raises: [IOError]
.}

Iterate over any line in the file f.

The trailing newline character(s) are removed from the iterated lines. Example:

proc countZeros(filename: File): tuple[lines, zeros: int] =
  for line in filename.lines:
    for letter in line:
      if letter == '0':
        result.zeros += 1
    result.lines += 1
  Source Edit
iterator items[T](a: seq[T]): T {.
inline
.}
iterates over each item of a.   Source Edit
iterator mitems[T](a: var seq[T]): var T {.
inline
.}
iterates over each item of a so that you can modify the yielded value.   Source Edit
iterator items(a: string): char {.
inline, raises: [], tags: []
.}
iterates over each item of a.   Source Edit
iterator mitems(a: var string): var char {.
inline, raises: [], tags: []
.}
iterates over each item of a so that you can modify the yielded value.   Source Edit
iterator `..<`[S, T](a: S; b: T): T
  Source Edit

Templates

template `!=`(x, y: untyped): untyped
unequals operator. This is a shorthand for not (x == y).   Source Edit
template `>=`(x, y: untyped): untyped
"is greater or equals" operator. This is the same as y <= x.   Source Edit
template `>`(x, y: untyped): untyped
"is greater" operator. This is the same as y < x.   Source Edit
template incl[T](s: var set[T]; flags: set[T])
includes the set of flags to the set x.   Source Edit
template excl[T](s: var set[T]; flags: set[T])
excludes the set of flags to x.   Source Edit
template `in`(x, y: untyped): untyped {.
dirty
.}
Sugar for contains
assert(1 in (1..3) == true)
assert(5 in (1..3) == false)
  Source Edit
template `notin`(x, y: untyped): untyped {.
dirty
.}
Sugar for not containing
assert(1 notin (1..3) == false)
assert(5 notin (1..3) == true)
  Source Edit
template `isnot`(x, y: untyped): untyped
Negated version of is. Equivalent to not(x is y).   Source Edit
template `>=%`(x, y: untyped): untyped
treats x and y as unsigned and compares them. Returns true iff unsigned(x) >= unsigned(y).   Source Edit
template `>%`(x, y: untyped): untyped
treats x and y as unsigned and compares them. Returns true iff unsigned(x) > unsigned(y).   Source Edit
template accumulateResult(iter: untyped)
helps to convert an iterator to a proc.   Source Edit
template newException(exceptn: typedesc; message: string;
                     parentException: ref Exception = nil): untyped
creates an exception object of type exceptn and sets its msg field to message. Returns the new exception object.   Source Edit
template stdmsg(): File
Template which expands to either stdout or stderr depending on useStdoutAsStdmsg compile-time switch.   Source Edit
template setupForeignThreadGc()
  Source Edit
template tearDownForeignThreadGc()
  Source Edit
template likely(val: bool): bool

Hints the optimizer that val is likely going to be true.

You can use this template to decorate a branch condition. On certain platforms this can help the processor predict better which branch is going to be run. Example:

for value in inputValues:
  if likely(value <= 100):
    process(value)
  else:
    echo "Value too big!"

On backends without branch prediction (JS and the nimscript VM), this template will not affect code execution.

  Source Edit
template unlikely(val: bool): bool

Hints the optimizer that val is likely going to be false.

You can use this proc to decorate a branch condition. On certain platforms this can help the processor predict better which branch is going to be run. Example:

for value in inputValues:
  if unlikely(value > 100):
    echo "Value too big!"
  else:
    process(value)

On backends without branch prediction (JS and the nimscript VM), this template will not affect code execution.

  Source Edit
template `&=`(x, y: typed)
generic 'sink' operator for Nim. For files an alias for write. If not specialized further an alias for add.   Source Edit
template `&=`(f: File; x: typed)
  Source Edit
template currentSourcePath(): string
returns the full file-system path of the current source   Source Edit
template assert(cond: bool; msg = "")
Raises AssertionError with msg if cond is false. Note that AssertionError is hidden from the effect system, so it doesn't produce {.raises: [AssertionError].}. This exception is only supposed to be caught by unit testing frameworks. The compiler may not generate any code at all for assert if it is advised to do so through the -d:release or --assertions:off command line switches.   Source Edit
template doAssert(cond: bool; msg = "")
same as assert but is always turned on and not affected by the --assertions command line switch.   Source Edit
template onFailedAssert(msg, code: untyped): untyped {.
dirty
.}
Sets an assertion failure handler that will intercept any assert statements following onFailedAssert in the current module scope.
# module-wide policy to change the failed assert
# exception type in order to include a lineinfo
onFailedAssert(msg):
  var e = new(TMyError)
  e.msg = msg
  e.lineinfo = instantiationInfo(-2)
  raise e
  Source Edit
template `..^`(a, b: untyped): untyped
a shortcut for '.. ^' to avoid the common gotcha that a space between '..' and '^' is required.   Source Edit
template `..<`(a, b: untyped): untyped {.
dirty
.}
a shortcut for '.. <' to avoid the common gotcha that a space between '..' and '<' is required.   Source Edit
template closureScope(body: untyped): untyped
Useful when creating a closure in a loop to capture local loop variables by their current iteration values. Example:
var myClosure : proc()
# without closureScope:
for i in 0 .. 5:
  let j = i
  if j == 3:
    myClosure = proc() = echo j
myClosure() # outputs 5. `j` is changed after closure creation
# with closureScope:
for i in 0 .. 5:
  closureScope: # Everything in this scope is locked after closure creation
    let j = i
    if j == 3:
      myClosure = proc() = echo j
myClosure() # outputs 3
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