From: Martin DeMello <martindemello@...>
Date: 2006-12-14T05:33:02+09:00
Subject: Re: map taking an argument (was: Re: join_with)

On 12/13/06, dblack@wobblini.net <dblack@wobblini.net> wrote:
>
> There was an RCR a while back, rejected by Matz, that asked for:
>
>    enum.map(:m)
>
> to be the same as:
>
>    enum.map {|e| e.m }
>
> It looks like Ruby >= 1.9 has this:
>
>    enum.map(&:m)
>
> which strikes me as the same thing, functionally, but visually noisier
> and semantically more obscure.
>
> I'm just wondering what the rationale is for rejecting the simple
> version and introducing the less simple one.

The 1.9 version is nicely orthogonal, though - it hasn't added
anything to #map, since the Symbol#to_proc method is called eagerly,
*before* passing the resultant proc to #map. And #map has always been
able to take a proc:

> (1..10).map &lambda {|i| i*2}
=> [2, 4, 6, 8, 10, 12, 14, 16, 18, 20]

So this hasn't really changed anything, it's just added a convenience
method to symbol. There's actually considerably less magic going on
than, say, #join's automatically converting everything to strings, and
the complexity is a result of that lack of magic.

martin