[Haskell-cafe] Code Golf

[Sjoerd Visscher]

Hi,

This one works for all 3 examples you gave:

diag = concat . takeWhile (not.null)
      . foldr1 (flip $ zipWith (flip (++)) . ([]:))
      . map ((++ repeat []) . map (:[]))

or, using Matt Hellige's pointless fun
http://matt.immute.net/content/pointless-fun

diag = foldr1 (zipWith (++) $. id ~> ([]:) ~> id)
      $. map (++ repeat []) ~> takeWhile (not.null)
      $. (map.map) (:[]) ~> concat

I think the second one is quite readable, thanks to Matt's notation.  
The essential part is up front, and the pre- and post-transformations  
that belong to each other can be grouped.

greetings,
--
Sjoerd Visscher
sjoerd at w3future.com