From: "Peña, Botp" <botp@...>
Date: 2008-09-12T10:27:16+09:00
Subject: Re: Advanced conditionals

From: David A. Black [mailto:dblack@rubypal.com] 
..
#For a little while, 1.9 allowed you to do this:
#>> e = [1,2,3].enum_for(:map, &lambda {|x| x * 10 })
#=> #<Enumerable::Enumerator:0x39038c>
#>> e.select {|n| n > 10 }
#=> [20, 30]
#But #enum_for no longer accepts a &block-style argument. The same code
#in current 1.9 would give you [], because it would ignore the lambda
#and just do a pass-through mapping.
#I'm still unclear as to why this behavior was removed. It seems to me
#that its removal reduces the usefulness of enumerators drastically.

maybe because it does not look any better than the simpler (but less efficient)

> e = [1,2,3].select{|n| n>1}.map{|x| x*10}
=>[20,30]

i was actually dreaming of ruby supporting multiple blocks
so that you can do simply

> e = [1,2,3].select{|n| n>1},{|x| x*10}
=>[20,30]

meaning, do a (re)map if a second code block is passed

kind regards -botp