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2014-04-21 Version 0.9.4 released

The Nimrod development community is proud to announce the release of version 0.9.4 of the Nimrod compiler and tools. Note: This release has to be considered beta quality! Lots of new features have been implemented but unfortunately some do not fulfill our quality standards yet.

Prebuilt binaries and instructions for building from source are available on the download page.

This release includes about 1400 changes in total including various bug fixes, new languages features and standard library additions and improvements. This release brings with it support for user-defined type classes, a brand new VM for executing Nimrod code at compile-time and new symbol binding rules for clean templates.

It also introduces support for the brand new Babel package manager which has itself seen its first release recently. Many of the wrappers that were present in the standard library have been moved to separate repositories and should now be installed using Babel.

Apart from that a new experimental Asynchronous IO API has been added via the asyncdispatch and asyncnet modules. The net and rawsockets modules have also been added and they will likely replace the sockets module in the next release. The Asynchronous IO API has been designed to take advantage of Linux's epoll and Windows' IOCP APIs, support for BSD's kqueue has not been implemented yet but will be in the future. The Asynchronous IO API provides both a callback interface and an interface which allows you to write code as you would if you were writing synchronous code. The latter is done through the use of an await macro which behaves similar to C#'s await. The following is a very simple chat server demonstrating Nimrod's new async capabilities.

import asyncnet, asyncdispatch

var clients: seq[PAsyncSocket] = @[]

proc processClient(client: PAsyncSocket) {.async.} =
  while true:
    let line = await client.recvLine()
    for c in clients:
      await c.send(line & "\c\L")

proc serve() {.async.} =
  var server = newAsyncSocket()
  server.bindAddr(TPort(12345))
  server.listen()
  
  while true:
    let client = await server.accept()
    clients.add client
    
    processClient(client)

serve()
runForever()

Note that this feature has been implemented with Nimrod's macro system and so await and async are no keywords.

Syntactic sugar for anonymous procedures has also been introduced. It too has been implemented as a macro. The following shows some simple usage of the new syntax:

import future

var s = @[1, 2, 3, 4, 5]
echo(s.map((x: int) => x * 5))

A list of changes follows, for a comprehensive list of changes take a look here.

Library Additions

  • Added macros.genSym builtin for AST generation.
  • Added macros.newLit procs for easier AST generation.
  • Added module logging.
  • Added module asyncdispatch.
  • Added module asyncnet.
  • Added module net.
  • Added module rawsockets.
  • Added module selectors.
  • Added module asynchttpserver.
  • Added support for the new asynchronous IO in the httpclient module.
  • Added a Python-inspired future module that features upcoming additions to the system module.

Changes affecting backwards compatibility

  • The scoping rules for the if statement changed for better interaction with the new syntactic construct (;).
  • OSError family of procedures has been deprecated. Procedures with the same name but which take different parameters have been introduced. These procs now require an error code to be passed to them. This error code can be retrieved using the new OSLastError proc.
  • os.parentDir now returns "" if there is no parent dir.
  • In CGI scripts stacktraces are shown to the user only if cgi.setStackTraceStdout is used.
  • The symbol binding rules for clean templates changed: bind for any symbol that's not a parameter is now the default. mixin can be used to require instantiation scope for a symbol.
  • quoteIfContainsWhite now escapes argument in such way that it can be safely passed to shell, instead of just adding double quotes.
  • macros.dumpTree and macros.dumpLisp have been made immediate, dumpTreeImm and dumpLispImm are now deprecated.
  • The nil statement has been deprecated, use an empty discard instead.
  • sockets.select now prunes sockets that are not ready from the list of sockets given to it.
  • The noStackFrame pragma has been renamed to asmNoStackFrame to ensure you only use it when you know what you're doing.
  • Many of the wrappers that were present in the standard library have been moved to separate repositories and should now be installed using Babel.

Compiler Additions

  • The compiler can now warn about "uninitialized" variables. (There are no real uninitialized variables in Nimrod as they are initialized to binary zero). Activate via {.warning[Uninit]:on.}.
  • The compiler now enforces the not nil constraint.
  • The compiler now supports a codegenDecl pragma for even more control over the generated code.
  • The compiler now supports a computedGoto pragma to support very fast dispatching for interpreters and the like.
  • The old evaluation engine has been replaced by a proper register based virtual machine. This fixes numerous bugs for nimrod i and for macro evaluation.
  • --gc:none produces warnings when code uses the GC.
  • A union pragma for better C interoperability is now supported.
  • A packed pragma to control the memory packing/alignment of fields in an object.
  • Arrays can be annotated to be unchecked for easier low level manipulations of memory.
  • Support for the new Babel package manager.

Language Additions

  • Arrays can now be declared with a single integer literal N instead of a range; the range is then 0..N-1.
  • Added requiresInit pragma to enforce explicit initialization.
  • Exported templates are allowed to access hidden fields.
  • The using statement enables you to more easily author domain-specific languages and libraries providing OOP-like syntactic sugar.
  • Added the possibility to override various dot operators in order to handle calls to missing procs and reads from undeclared fields at compile-time.
  • The overload resolution now supports static[T] params that must be evaluable at compile-time.
  • Support for user-defined type classes has been added.
  • The command syntax is supported in a lot more contexts.
  • Anonymous iterators are now supported and iterators can capture variables of an outer proc.
  • The experimental strongSpaces parsing mode has been implemented.
  • You can annotate pointer types with regions for increased type safety.
  • Added support for the builtin spawn for easy thread pool usage.

Tools improvements

  • c2nim can deal with a subset of C++. Use the --cpp command line option to activate.