16 May
2008
16 May
'08
12:02 p.m.
On Fri, May 16, 2008 at 07:58:40AM -0400, Dan Doel wrote:
On Friday 16 May 2008, leledumbo wrote:
I don't know how Haskell should behave on this. Consider this function: elemOf (x,y) = (x,y) `elem` [ (a,b) | a <- [0..], b <- [0..] ]
FYI: The control-monad-omega package on hackage.haskell.org can handle this sort of thing (liberties taken with ghci formatting):
Prelude> :m + Control.Monad.Omega Prelude Control.Monad.Omega> (1,1) `elem` runOmega (do x <- each [0..] ; y <- each [0..] ; return (x,y)) True Prelude Control.Monad.Omega>
It does breadth-first instead of depth-first search.
You could also just use [ (b,a-b) | a <- [0..], b <- [0..a]] David