From: Avi Bryant <avi@...4.com>
Date: 2001-10-27T03:48:07+09:00
Subject: [ruby-talk:23488] Re: simplified use of map

Robert Feldt wrote:

>Change map to take an optional parameter which is a Symbol which
>is sent to each element (as a message).
>Example:

>[1,2].map(:succ)  #=> [2,3]

>I know that you can do it with

>[1,2].map {|e| e.succ}

You might want to look at Marcel Weiher's Higher Order Messaging for Obj-C
and Squeak... this makes use of "trampoline" objects to do the same thing
like this:

[1,2].map.succ  #=> [2,3]

It is perhaps harder to immediately understand (I find it easier for some
reason in the  Obj-C/Smalltalk syntax), but it has the advantage that the
method being called can take parameters:

["abc", "cba"].map.tr("a", "z")  #=> ["zbc", "cbz"]

or even:

[1,2].map + 1  #=> [2,3]

or:

[1..10].select < 5
	#=> [1,2,3,4]


It's not hard to implement; I may take a stab at it later today when I
have time.

Avi