From: Pixel <pixel@...>
Date: 2002-09-27T20:58:37+09:00
Subject: Re: Ruby - common pitfalls?

matz@ruby-lang.org (Yukihiro Matsumoto) writes:

> |Or perhaps instead:
> |
> |  a.zipWith! (b) do |x, y| x + y end # slightly resembling Haskell
> |  a = b.zipWith (c) do |x, y| x + y end
> |
> |which is a bit more verbose, but can be done with the current syntax.
> 
> iff it has a better name than zipWith.

many languages use the "map" function for this. what about this:

module Enumerable
  def map(*ls)
    i = 0
    collect{|e| 
      l = [e] + ls.collect{|l| l[i]}
      i += 1
      yield(*l)      
    }
  end
end

p [1, 2].map([3, 4], [5, 6]){|a,b,c| a+b+c}
#=> [9, 12]

?

(http://merd.net/pixel/language-study/syntax-across-languages/BagAndLst.html#BagAndLstTrnTwoLstInPrl)

     * transform two lists in parallel
                                      
       map2                     OCaml 
       zipWith                  Haskell
       Zip                      Oz     
       map                      Dylan, Python, Scheme
       mapcar                   Common Lisp                                                           
       l1 with: l2 collect: ... Smalltalk     
       transform                C++
       ListPair.map             SML