From: Ryan Leavengood <leavengood@...>
Date: 2005-10-20T03:59:50+09:00
Subject: Re: Functional with Ruby

On 10/19/05, Andreas Semt <Andreas.Semt@gmx.net> wrote:
> Hello list,
>
> here a really simple Haskell function, which sums all elements of a list
> (from the book "The Haskell School of Expression"):
> --------------------------------
> listSum [] = 0
> listSum (x : xs) = x + listSum xs
> --------------------------------
>
> Which is the best way to say it in Ruby (functional style)? Don't use
> 'enum.inject', please!

What's wrong with inject? I find this very readable and not any more
verbose than the Haskell:

irb(main):001:0> a=[1,2,3,4,5,6,7]
=> [1, 2, 3, 4, 5, 6, 7]
irb(main):002:0> a.inject(0){|i,sum| i+sum}
=> 28
irb(main):003:0> 1+2+3+4+5+6+7
=> 28
irb(main):004:0> module Enumerable
irb(main):005:1> def list_sum
irb(main):006:2> self.inject(0){|i,sum| i+sum}
irb(main):007:2> end
irb(main):008:1> end
=> nil
irb(main):009:0> a.list_sum
=> 28

Ryan