[ANN] LuaMacro on LuaForge

["steve donovan" <steve.j.donovan@...>]

Hi guys,

A semi-official release:

http://luaforge.net/projects/luamacro/

The macro du jour is list comprehensions, using a syntax suggested by
Fabien and implemented with his MetaLua:

    x = L{i for i = 1,5}

    {1,2,3,4,5}

Such a statement does not actually require much transformation to be
valid Lua, if you use anonymous functions:

   x = (function() local ls={}; for i = 1,5 do ls[#ls+1] = i; return ls end)()

It's possible to nest these 'list constructors' (I personally don't
like the term 'list comprehension')

x = L{L{j for j=1,3} for i=1,3}

  {{1,2,3},{1,2,3},{1,2,3}}

There is also an implementation of the match/with statement as
discussed some time back.

Note: there is a limitation of macros; they cannot load modules,
except with a nasty fiddle:

For example, a simple macro which has the side-effect of trying to
load a module. If one switches off the token filter by setting FILTER
to nil, it seems to work.

macro.define('X',nil,function(ls)
       local F = FILTER
       FILTER = nil
       require 'simple'
       FILTER = f
       return {}
end)

Thanks to Sérgio Medeiros for unearthing this bug.

steve d.