Re: map/grep in Lua: Shedding My Functional Perlisms

[Veli-Pekka Tätilä <vtatila@...>]

Ben Kelly wrote:
> If using alpha compilers gives you the heebie jeebies,
I've taken a quick glance at both metalua and luasub before, and while 
greastly powerful both do have a learning curve. I would probably get into 
them if I needed major syntax mods, but this is only a small annoyance at 
best.

you can also do
> something like this:
>
> function L(args)
>  return function(exp)
>    return assert(loadstring("return function("..args..")"
>      .." return "..exp.." end"))()
>  end
> end
<snippage>
> And a simple map that inverts the truth value of each element:
> map(L "e" "not e", list)
Ah that's great, I like this solution in that it will run almost anywhere. 
I'm using Lua plus and cannot in genral add other modules in it, as I'm 
scripting a screen reader program at work. This solution reminds me of how 
you need to eval the tr operator in Perl to get it to eval lists known at 
runtime. Both evaluate code Perl to get around built-in limits, Lua here to 
make the syntax a whole lot nicer.

Thanks for posting this trick.
BTW, I won't be here to anser threads for a few days.

--
With kind regards Veli-Pekka Tätilä
Accessibility, Apps and Coding plus Synths and Music:
http://vtatila.kapsi.fi