leafo / moonscript

Windows binary: https://github.com/leafo/moonscript/releases/tag/win32-v0.5.0

Syntax updates

Function calls

Function calls with parentheses can now have free whitespace around the
arguments. Additionally, a line break may be used in place of a comma:

my_func(
  "first arg"
  =>
    print "some func"

  "third arg", "fourth arg"
)

Function argument definitions

Just like the function all update, function argument definitions have no
whitespace restrictions between arguments, and line breaks can be used to
separate arguments:

some_func = (
  name
  type
  action="print"
) =>
  print name, type, action

Additions

• elseif can be used part of an unless block (nymphium)
• unless conditional expression can contain an assignment like an if statement (#251)
• Lua 5.3 bitwise operator support (nymphium) (Kawahara Satoru)
• Makefile is Lua version agnostic (nymphium)
• Lint flag can be used with moonc watch mode (ChickenNuggers)
• Lint exits with status 1 if there was a problem detected (ChickenNuggers)
• Compiler can be used with lulpeg

Bug Fixes

• Slice boundaries can be full expressions (#233)
• Destructure works when used as loop variable in comprehension (#236)
• Proper name local hoisting works for classes again (#287)
• Quoted table key literals can now be parsed when table declaration is in single line (#286)
• Fix an issue where else could get attached to wrong if statement (#276)
• Loop variables will no longer overwrite variables of the same name in the same scope (egonSchiele)
• A file being deleted will not crash polling watch mode (ChickenNuggers)
• The compiler will not try to compile a directory ending in .moon (Gskartwii)
• alt_getopt import works with modern version (Jon Allen)
• Code coverage not being able to find file from chunk name

You can now find windows binaries through GithHub's releases. See win32-v0.4.0

Changes to super

super now looks up the parent method via the class reference, instead of a
(fixed) closure to the parent class.

Given the following code:

class MyThing extends OtherThing
  the_method: =>
    super!

In the past super would compile to something like this:

_parent_0.the_method(self)

Where _parent_0 was an internal local variable that contains a reference to
the parent class. Because the reference to parent is an internal local
variable, you could never swap out the parent unless resorting to the debug
library.

This version will compile to:

_class_0.__parent.__base.the_method(self)

Where _class_0 is an internal local variable that contains the current class (MyThing).

Another difference is that the instance method is looked up on __base instead
of the class. The old variation would trigger the metamethod for looking up on
the instance, but a class method of the same name could conflict, take
precedence, and be retuned instead. By referencing __base directly we avoid
this issue.

Super on class methods

super can now be used on class methods. It works exactly as you would expect.

class MyThing extends OtherThing
  @static_method: =>
    print super!

Calling super will compile to:

_class_0.__parent.static_method(self)

Improved scoping for super

The scoping of super is more intelligent. You can warp your methods in other
code and super will still generate correctly. For example, syntax like this
will now work as expected:

class Sub extends Base
  value: if debugging
    => super! + 100
  else
    => super! + 10

  other_value: some_decorator {
    the_func: =>
      super!
  }

super will refer to the lexically closest class declaration to find the name
of the method it should call on the parent.

Bug Fixes

• Nested with blocks used incorrect ref (#214 by @geomaster)
• Lua quote string literals had wrong precedence (#200 by @nonchip)
• Returning from with block would generate two return statements (#208)
• Including return or break in a continue wrapped block would generate invalid code (#215 #190 #183)

Other

• Refactor transformer out into multiple files
• moon command line script rewritten in MoonScript
• moonscript.parse.build_grammar function for getting new instance of parser grammar
• Chain AST updated to be simpler

I'm happy to announce MoonScript version 0.2.4, the CoffeeScript inspired language that compiles to Lua. It's been about 5 months since the last release.

As always, if you've got any questions or want to tell me about how you are using MoonScript you can email me or contact me on twitter.

You can find the full release notes on my blog: http://leafo.net/posts/moonscript_v024.html

Changes

• The way the subtraction operator works has changed. There was always a little confusion as to the rules regarding whitespace around it and it was recommended to always add whitespace around the operator when doing subtraction. Not anymore. Hopefully it now works how you would expect. (a-b compiles to a - b and not a(-b) anymore).
• The moon library is no longer sets a global variable and instead returns the module. Your code should now be:

moon = require "moon"

• Generated code will reuse local variables when appropriate. Local variables are guaranteed to not have side effects when being accessed as opposed to expressions and global variables. MoonScript will now take advantage of this and reuse those variable without creating and copying to a temporary name.
• Reduced the creation of anonymous functions that are called immediately.
  MoonScript uses this technique to convert a series of statements into a single expression. It's inefficient because it allocates a new function object and has to do a function call. It also obfuscates stack traces. MoonScript will flatten these functions into the current scope in a lot of situations now.
• Reduced the amount of code generated for classes. Parent class code it left out if there is no parent.

New Things

• You can now put line breaks inside of string literals. It will be replaced with \n in the generated code.

x = "hello
world"

• Added moonscript.base module. It's a way of including the moonscript module without automatically installing the moonloader.
• You are free to use any whitespace around the name list in an import statement. It has the same rules as an array table, meaning you can delimit names with line breaks.

import a, b
  c, d from z

• Added significantly better tests. Previously the testing suite would only verify that code compiled to an expected string. Now there are unit tests that execute the code as well. This will make it easier to change the generated output while still guaranteeing the semantics are the same.

Bug Fixes

• b is not longer treated as self assign in { a : b }
• load functions will return nil instead of throwing error, as described in documentation
• fixed an issue with moon.mixin where it did not work as described

Other Stuff

Libraries

Some updates for libraries written in MoonScript:

• Lapis, the MoonScript powered web framework has come out with version
  0.0.2.
• magick, LuaJIT FFI bindings to ImageMagick
• web_sanitize, HTML sanitization

Games

Ludum Dare happened again, and I wrote another game in MoonScript:

• Moondar (source)

Thanks

Thanks to everyone who provided feedback for this release. See you next time.