Re: Lua is not skin deep

[Asko Kauppi <askok@...>]

The problem with the error messages is that what the eventual Lua  
parser sees is not what the user saw.

Let's say we have these "skins" (might be a very bad example):

#...		->	(select('#',...))
...[exp]	->	(select(exp,...))

I don't think any static error in 'exp' can rock this, but if there's  
something at runtime, Lua will report the function "select" to be  
involved. What select? the user might ask, since he's probably never  
seen one.

-asko


steve donovan kirjoitti 31.10.2007 kello 15:31:

> That is very cool - you are doing transforms on the AST
> representation, but the AST can be 'quoted'. I enjoyed Lisp in the
> 80s, but eventually got tired of writing programs virtually in raw
> AST.
>
> But, to refer to the point about losing lexical information; since
> token filter extensions are hooked into the raw token stream, they can
> actually give pretty appropriate error messages.
>
> steve d.
>
> On 10/31/07, Fabien <fleutot+lua@gmail.com> wrote:
> >  -{block:
> > mlp.stat:add{ 'try', mlp.block, 'except', mlp.block, 'end', builder =
> > exn_builder }
> > function exn_builder(args)
> >     local try_block, exn_block = unpack(args)
> >     return +{stat:
> >       do
> >          local status, exn = pcall(function() -{try_block} end)
> >           if not status then -{exn_block} end
> >       end }
> > end }