CHANGELOG.md

MoonScript v0.5.0 (2016-9-25)

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

MoonScript v0.4.0 (2015-12-06)

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

MoonScript v0.3.2 (2015-6-01)

Bug Fixes

• package.moonpath geneator does not use paths that don't end in lua

MoonScript v0.3.1 (2015-3-07)

Bug Fixes

• Fixed a bug where an error from a previous compile would prevent the compiler from running again

MoonScript v0.3.0 (2015-2-28)

New Features

• New unused assignment linter finds assignments that are never referenced after being defined.

Parsing Updates

Whitespace parsing has been relaxed in a handful of locations:

• You can put unrestricted whitespace/newlines after operator in a binary operator before writing the right hand side. The following are now valid:

x = really_long_function! +
  2304

big_math = 123 /
  12 -
  43 * 17


bool_exp = nice_shirt and cool_shoes or
  skateboard and shades

• You can put unrestricted whitespace/newlines immediately after an opening parenthesis, and immediately before closing parenthesis. The following are now valid:

hello = 100 + (
  var * 0.23
) - 15


funcall(
  "height", "age", "weight"
)


takes_two_functions (->
  print "hello"
), ->
  print "world"

• You can put unrestricted whitespace/newlines immediately after a : when defining a table literal. The following is now valid:

x = {
  hello:
    call_a_function "football", "hut"
}

Code Generation

• Single value import/destructure compiles directly into single assignment

Bug Fixes

• Some moonc command line flags were being ignored
• Linter would not report global reference when inside self assign in table
• Fixed an issue where parser would crash in Lpeg 0.12 when compiling hundreds of times per process

Misc

• MoonScript parser now written in MoonScript

MoonScript v0.2.6 (2014-6-18)

Bug Fixes

• Fixes to posmap generation for multi-line mappings and variable declarations
• Prefix file name with @ when loading code so stack traces tread it as file
• Fix bug where moonc couldn't work with absolute paths
• Improve target file path generation for moonc

MoonScript v0.2.5 (2014-3-5)

New Things

• New code coverage tool built into moonc
• New linting tool built into moonc, identifies global variable references that don't pass whitelist
• Numbers can have LL and ULL suffixes for LuaJIT

Bug Fixes

• Error messages from moonc are written to standard error
• Moonloader correctly throws error when moon file can't be parsed, instead of skipping the module
• Line number rewriting is no longer incorrectly offset due to multiline strings

Code Generation

Bound functions will avoid creating an anonymous function unless necessary.

x = hello\world

Before:

local x = (function()
  local _base_0 = hello
  local _fn_0 = _base_0.world
  return function(...)
    return _fn_0(_base_0, ...)
  end
end)()

After:

local x
do
  local _base_0 = hello
  local _fn_0 = _base_0.world
  x = function(...)
    return _fn_0(_base_0, ...)
  end
end

Explicit return statement now avoids creating anonymous function for statements where return can be cascaded into the body.

->
  if test1
    return [x for x in *y]

  if test2
    return if true
      "yes"
    else
      "no"

  false

Before:

local _
_ = function()
  if test1 then
    return (function()
      local _accum_0 = { }
      local _len_0 = 1
      local _list_0 = y
      for _index_0 = 1, #_list_0 do
        local x = _list_0[_index_0]
        _accum_0[_len_0] = x
        _len_0 = _len_0 + 1
      end
      return _accum_0
    end)()
  end
  if test2 then
    return (function()
      if true then
        return "yes"
      else
        return "no"
      end
    end)()
  end
  return false
end

After:

local _
_ = function()
  if test1 then
    local _accum_0 = { }
    local _len_0 = 1
    local _list_0 = y
    for _index_0 = 1, #_list_0 do
      local x = _list_0[_index_0]
      _accum_0[_len_0] = x
      _len_0 = _len_0 + 1
    end
    return _accum_0
  end
  if test2 then
    if true then
      return "yes"
    else
      return "no"
    end
  end
  return false
end

MoonScript v0.2.4 (2013-07-02)

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

MoonScript v0.2.3-2 (2013-01-29)

Fixed bug with moonloader not loading anything

MoonScript v0.2.3 (2013-01-24)

Changes

• For loops when used as expressions will no longer discard nil values when accumulating into an array table. This is a backwards incompatible change. Instead you should use the continue keyword to filter out iterations you don't want to keep. Read more here.
• The moonscript module no longer sets a global value for moonscript and instead returns it. You should update your code:

moonscript = require "moonscript"

New Things

• Lua 5.2 Support. The compiler can now run in either Lua 5.2 and 5.1
• A switch when clause can take multiple values, comma separated.
• Added destructuring assignment.
• Added local * (and local ^) for hoisting variable declarations in the current scope
• List comprehensions and line decorators now support numeric loop syntax

Bug Fixes

• Numbers that start with a dot, like .03, are correctly parsed
• Fixed typo in fold library function
• Fix declaration hoisting inside of class body, works the same as local * now

Other Stuff

MoonScript has made its way into GitHub. .moon files should start to be recognized in the near future.

MoonScript v0.2.2 (2012-11-03)

Changes

• Compiled files will now implicitly return their last statement. Be careful, this might change what require returns.

New Things

The Language

• Added continue keyword for skipping the current iteration in a loop.
• Added string interpolation.
• Added do expression and block.
• Added unless as a block and line decorator. Is the inverse of if.
• Assignment can be used in an if statement's expression.
• Added or= and and= operators.
• @@ can be prefixed in front of a name to access that name within self.__class
• @ and @@ can be used as values to reference self and self.__class.
• In class declarations it's possible to assign to the class object instead of the instance metatable by prefixing the key with @.
• Class methods can access locals defined within the body of the class declaration.
• Super classes are notified when they are extended from with an __inherited callback.
• Classes can now implicitly return and be expressions.
• local keyword returns, can be used for forward declaration or shadowing a variable.
• String literals can be used as keys in table literals.
• Call methods on string literals without wrapping in parentheses: "hello"\upper!
• Table comprehensions can return a single value that is unpacked into the key and value.
• The expression in a with statement can now be an assignment, to give a name to the expression that is being operated on.

The API

• The load functions can take an optional last argument of options.

The Tools

• The online compiler now runs through a web service instead of emscripten, should work reliably on any computer now.
• Windows binaries have been updated.

Bug Fixes

• Significantly improved the line number rewriter. It should now accurately report all line numbers.
• Generic for loops correctly parse for multiple values as defined in Lua.
• Update expressions don't fail with certain combinations of precedence.
• All statements/expressions are allowed in a class body, not just some.
• x = "hello" if something will extract the declaration of x if it's not in scope yet. Preventing an impossible to access variable from being created.
• varargs, ..., correctly bubble up through automatically generated anonymous functions.
• Compiler doesn't crash if you try to assign something that isn't assignable.
• Numerous other small fixes. See commit log.

MoonScript v0.2.0 (2011-12-12)

Changes

• , is used instead of : for delimiting table slice parts.
• Class objects store the metatable of their instances in __base. __base is also used in inheritance when chaining metatables.

New Things

The Language

• Added key-value table comprehensions.
• Added a switch statement.
• The body of a class can contain arbitrary expressions in addition to assigning properties. self in this scope refers to the class itself.
• Class objects themselves support accessing the properties of the superclass they extend (like instances).
• Class objects store their name as a string in the __name property.
• Enhanced the super keyword in instance methods.
• Bound methods can be created for an object by using object\function_name as a value. Called function stubs.
• Added export * statement to export all assigned names following the statement.
• Added export ^ statement to export all assigning names that begin with a capital letter following the statement.
• export can be used before any assignment or class declaration to export just that assignment (or class declaration).
• Argument lists can be broken up over several lines with trailing comma.
• :hello is short hand for hello: hello inside of table literal.
• Added ..= for string concatenation.
• table.insert no longer used to build accumlated values in comprehensions.

The API

• Added loadfile, loadstring, and dofile functions to moonscript module to load/run MoonScript code.
• Added to_lua function to moonscript module to convert a MoonScript code string to Lua string.

The Tools

• Created prebuilt MoonScript Windows executables.
• Wrote a Textmate/Sublime Text bundle.
• Wrote a SciTE syntax highlighter with scintillua.
• Created a SciTE package for Windows that has everything configured.
• Created an online compiler and snippet site using emscripten.
• Watch mode works on all platforms now. Uses polling if inotify is not available.

Standard Library

I'm now including a small set of useful functions in a single module called moon:

require "moon"

Documentation is available here.

Bug Fixes

• Windows line endings don't break the parser.
• Fixed issues when using ... within comprehensions when the compiled code uses an intermediate function in the output.
• Names whose first characters happen to be a keyword don't break parser.
• Return statement can have no arguments
• argument names prefixed with @ in function definitions work outside of classes work with default values.
• Fixed parse issues with the shorthand values within a with block.
• Numerous other small fixes. See commit log.

Other Stuff

Since the first release, I've written one other project in MoonScript (other than the compiler). It's a static site generator called sitegen. It's what I now use to generate all of my project pages and this blog.

MoonScript 0.1.0 (2011-08-12)

Initial release