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

["Vyacheslav Egorov" <mister.aleph@...>]

> The problem to me is the syntax

Syntax is not a problem. Just use metalua :)

--
e.v.e

On Mon, Aug 11, 2008 at 12:03 AM, Veli-Pekka Tätilä <vtatila@gmail.com> wrote:
> Hi list,
> Does anyone use short anonymous functions with Lua ports of higher-order
> stuff like map, grep (filter), reduce, zip and the rest of the lot? I use
> these things a lot in Perl and Ruby and was wondering why they aren't part
> of the standard library. Until recently, that is, when I ported some of
> those functions to lua as coroutine based iterators, and discovered the hard
> way they are not practical quite the same way as in the other scripting
> languages. This is not a complaint, just an observation.
>
> The problem to me is the syntax. A map doing nothing looks lie:
>
> map(function(e) return e end, list)
>
> Quite a lot of typing and as soon as the processing gets much more complex,
> you might as well give the callback function a name in the first place.
> compared to just (Perl):
>
> map $_, @list;
>
> or
>
> map { $_ } @list;
>
> So the fact that you do need to name your parameters, do need the return
> keyword, the keyword for function being function rather than def or sub
> etc... majorly contributes to this. NOt only that but Perl has a lot of
> magic related to the $_ variable, making code using it quite short. map is
> also, in that language, great for populating hashes based on assigning
> subsequent list elements, mapping file names to their sizes, for example:
>
> my %hash = map { $_, -s } <*.txt>;
>
> Again, Lua does not have all that syntactic sugar to make this very useful.
> I don't think it should, either.
>
> In Perl and Ruby (in the little I've coded the latter) the one final idiom I
> use is list processing statements that do many things e.g. two maps, map and
> a grep etc... Because the syntax is not verbose, the PErl version is brief.
> and because they are chained method calls, the Ruby version reads left to
> right, which I find to be a huge advantage when reading code with a speech
> synth. stuff such as (untested, slightly modded from old code of mine):
>
> def rgb_dif firstRgb, secondRgb
> (firstRgb.zip secondRgb).map do|component|
>  (component[0] - component[1]).abs
> end
> end
>
> This is just something I thought I'd post about seeing the recent thread on
> assignment statements. Speaking of Perl and Lua, even as a newbie to the
> language,I like Lua immensely and found it easy to pick up due to the strong
> perl parallelisms like heavy use of hashes and the OOP. Because of that I
> have a tutorial for Perlers, though be warned, the text is alpha quality:
>
> http://vtatila.kapsi.fi/luatut.html
>
> PS: in a way the anonymous function syntax of Lua is extremely logical. Like
> a function without the name, with the parameter list, return statement and
> all.
>
> --
> With kind regards Veli-Pekka Tätilä
> Accessibility, Apps and Coding plus Synths and Music:
> http://vtatila.kapsi.fi
>
>