Hi, Depending on what you want, you should either remove 'return' or change to 'foldM' (from Control.Monad). If you choose the latter, you also need to add a type signature to f (because of the monomorphism restriction). / Emil On 2007-12-04 14:43, Rafael wrote:
Hi... I give this error using hugs for the code:
--------------------------------------------------- f = foldl (\x y -> add x y) 0 [1,2,3] add x y = return (x + y) --------------------------------------------------- I try:
f = foldl (\x y -> counter x y) (return 0) [1,2,3]
but it dont solve, and with ghci:
" Occurs check: cannot construct the infinite type: b = m b Expected type: b Inferred type: m b In the expression: add x y In a lambda abstraction: \ x y -> add x y "
thnks.
att Rafael _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe