Re: [Haskell-cafe] comprehension generators from IO [a]'s ?

On Mon, Dec 19, 2005 at 01:42:19PM -0600, Steve Harris wrote:

What I'm after is something like: -- (psuedo-code) [(b,c,d) | b <- getDirectoryContents a_dir, c <- getDirectoryContents (a_dir ++ "/" ++ b), d <- getDirectoryContents (a_dir ++ "/" ++ b ++ "/" ++ c) ],

Check out Control.Monad.List.ListT, which combines list non-determinism with another monad. Eg, ListT (getDirectoryContents a_dir) :: ListT IO FilePath Andrew