3 ms·

The point of a list comprehension is often that it can work with multiple lists. This can't do that, can it?

• listcomp 14y ago
  That can't, but with https://gist.github.com/605891 https://gist.github.com/605891 you can, using syntax like: [(1..6),(4..6),(7..9)].comprehension { |a, b, c| a + b + c if a % 2 == 0 } And if you go to extremes like https://gist.github.com/3356675 https://gist.github.com/3356675 you can use Haskell-like syntax: [a + b | a <- ['n','p'..'t'], b <- %w[a i u e o]] Ruby's blocks and method_missing are very powerful.
  • zachallaun 14y ago
    That second example is awesome! And it demonstrates that I don't know nearly enough about Ruby. :) Thanks for contributing it.
    • listcomp 14y ago
      You're welcome! Just to be clear, I am not the original author. I was impressed with it myself. :)
  • draegtun 14y ago
    Very nice indeed. NB. Correction to my earlier comment elsewhere here about List::Gen & multiple lists because it does provide cross combinators and also gather/take which is a perl6 way of doing complicated (multi) list comprehensions. Here are the two examples written in perl6 (which do work in Rakudo). gather for 1..6 X 4..6 X 7..9 -> $a, $b, $c { take $a + $b + $c if $a %% 2 } gather for ('n', 'p'..'t') X <a i u e o> -> $a, $b { take $a ~ $b }