From: Dave Burt <dave@...>
Date: 2005-07-31T23:26:03+09:00
Subject: Re: Higher Order Functions

>>   Functional.every(proc{|x| x * 2}, [1, 2, 3])
>
> IMO, you should pass a block.
>
> Then, you still can call it like that:
>
>  Functional.every [1,2,3], &method(:foo)

And better yet (IMO) is Ruby's own
  [1, 2, 3].collect &method(:foo)

In the spirit of the thing, I'd prefer these functions to be first-class 
themselves. Perhaps the most obvious way to do this is:
  module Functional
    def every
      proc do |f, lst|
        lst.collect {|element| f[element] }
      end
    end
  end

Which could be used like this:
  f = Functional.every
  g = proc {|x| x * 2 }
  p f[g, [1, 2, 3]]

I'm not up with procs taking blocks; I think it can't be done. And if not, 
that's a barrier to using blocks in higher-order functions. You can pass 
them as parameters, of course, as in my example.

This is Lispy, though - use square-brackets instead of "call" and you'll 
have more brackets than alphanums before you know it!

Cheers,
Dave