Version 0.9.2 released

We are pleased to announce that version 0.9.2 of the Nimrod compiler has been released. This release has attracted by far the most contributions in comparison to any other release.

This release brings with it many new features and bug fixes, a list of which can be seen later. One of the major new features is the effect system together with exception tracking which allows for checked exceptions and more, for further details check out the manual . Another major new feature is the introduction of statement list expressions, more details on these can be found here. The ability to exclude symbols from modules has also been implemented, this feature can be used like so: import module except symbol.

Thanks to all contributors!


  • The old GC never collected cycles correctly. Fixed but it can cause performance regressions. However you can deactivate the cycle collector with GC_disableMarkAndSweep and run it explicitly at an appropriate time or not at all. There is also a new GC you can activate with --gc:markAndSweep which does not have this problem but is slower in general and has no realtime guarantees.
  • cast for floating point types now does the bitcast as specified in the manual. This breaks code that erroneously uses cast to convert different floating point values.
  • SCGI module’s performance has been improved greatly, it will no longer block on many concurrent requests.
  • In total fixed over 70 github issues and merged over 60 pull requests.

Library Additions

  • There is a new experimental mark&sweep GC which can be faster (or much slower) than the default GC. Enable with --gc:markAndSweep.
  • Added system.onRaise to support a condition system.
  • Added system.locals that provides access to a proc’s locals.
  • Added macros.quote for AST quasi-quoting.
  • Added system.unsafeNew to support hacky variable length objects.
  • system.fields and system.fieldPairs support object too; they used to only support tuples.
  • Added system.CurrentSourcePath returning the full file-system path of the current source file.
  • The macros module now contains lots of useful helpers for building up abstract syntax trees.

Changes affecting backwards compatibility

  • shared is a keyword now.
  • Deprecated sockets.recvLine and asyncio.recvLine, added readLine instead.
  • The way indentation is handled in the parser changed significantly. However, this affects very little (if any) real world code.
  • The expression/statement unification has been implemented. Again this only affects edge cases and no known real world code.
  • Changed the async interface of the scgi module.
  • WideStrings are now garbage collected like other string types.

Compiler Additions

  • The doc2 command does not generate output for the whole project anymore. Use the new --project switch to enable this behaviour.
  • The compiler can now warn about shadowed local variables. However, this needs to be turned on explicitly via --warning[ShadowIdent]:on.
  • The compiler now supports almost every pragma in a push pragma.
  • Generic converters have been implemented.
  • Added a highly experimental noforward pragma enabling a special compilation mode that largely eliminates the need for forward declarations.

Language Additions

  • case expressions are now supported.
  • Table constructors now mimic more closely the syntax of the case statement.
  • Nimrod can now infer the return type of a proc from its body.
  • Added a mixin declaration to affect symbol binding rules in generics.
  • Exception tracking has been added and the doc2 command annotates possible exceptions for you.
  • User defined effects (“tags”) tracking has been added and the doc2 command annotates possible tags for you.
  • Types can be annotated with the new syntax not nil to explicitly state that nil is not allowed. However currently the compiler performs no advanced static checking for this; for now it’s merely for documentation purposes.
  • An export statement has been added to the language: It can be used for symbol forwarding so client modules don’t have to import a module’s dependencies explicitly.
  • Overloading based on ASTs has been implemented.
  • Generics are now supported for multi methods.
  • Objects can be initialized via an object constructor expression.
  • There is a new syntactic construct (;) unifying expressions and statements.
  • You can now use from module import nil if you want to import the module but want to enforce fully qualified access to every symbol in module.

Notes for the future

  • The scope rules of if statements will change in 0.9.4. This affects the =~ pegs/re templates.
  • The sockets module will become a low-level wrapper of OS-specific socket functions. All the high-level features of the current sockets module will be moved to a network module.