Re: still about switch..

[Rici Lake <lua@...>]

On 7-Sep-04, at 3:45 PM, Eric Tetz wrote:

> Asko Kauppi wrote:
> > What do you think, or should I just shut up? :)
>
> I've always thought it would be nice to have some syntatical sugar for
> a closure, especially where there are no parameters.

In a way, it is unfortunate that the same keyword is used both for 
function statements and for function constructors, although no 
syntactic ambiguity arises. However, this does force the use of () to 
indicate that the closure has no arguments. Moreover, it makes it more 
complicated to allow the use of free-standing closures as 
parenthesis-free arguments, although that is possibly not a good idea.

I don't think overloading "do" is great, either. Do (at least in 
English) implies a certain urgency; one would naturally expect the 
chunk to be "done", rather than stored for later usage. Writing 
closures as "function() ... end" is only slightly wordier.

If I had one syntactic sugar wish with respect to functions, it would 
be to allow the use of
function [:]key(arg) ... end in a table constructor, so that one could 
write, for example: (Quoting something I see in front of me)

function Memoise(fn)
  return withmeta {
    function :__index(key)
      if key then
        local rv = fn(key); self[key] = rv; return rv
      end
    end,
    function :__call(key)
      local rv, err = rawget(self, key)
      if rv == nil then
         rv, err = fn(key)
         self[key] = rv
      end
      return rv, err
    end
  }
end

rather than the somewhat clumsier version with __index = function(self, 
key) ...

Note:
  function withmeta(meta) return setmetatable({}, meta) end

  purely for syntactic convenience :)