Re: [Haskell-cafe] pythags

Check out Hoogle: http://haskell.org/hoogle/?q=guard import Control.Monad -Greg On 2/12/07, phiroc@free.fr wrote:

Hello,

the "Advanced Monads" page in the Haskell Wikibook (http://en.wikibooks.org/wiki/Haskell/Advanced_monads) contains the following example of a List Monad

pythags = do x <- [1..] y <- [x..] z <- [y..] guard (x^2 + y^2 == z^2) return (x, y, z)

However, whenever you load that function definition into Hugs or GHCi, you get a message saying that "guard" is an undefined variable.

Does anyone know why?

Thanks.

phiroc _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe