# Version 0.9.4 released

### 2014年04月21日 Dominik Picheta

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.