the 'sequence' prelude function does exactly what you want.
It's implemented as
sequence ms = foldr k (return []) ms
where
k m m' = do { x <- m; xs <- m'; return (x:xs) }
On 5/4/07, Phlex
Hello all,
I'm trying to learn haskell, so here's is my first newbie question. I hope this list is appropriate for such help requests.
I'm trying to write a function with the signature [IO Int] -> IO [Int]
Here is my first attempt :
conv :: [IO Int] -> IO [Int] conv l = do val <- (head l) return (val : (conv (tail l)))
This does not work as I'm consing an Int to an (IO [Int]). So I tried this :
conv2 :: [IO Int] -> IO [Int] conv2 l = do val <- (head l) rest <- (conv2 (tail l)) return (val : rest)
That works, but it won't work for infinite lists. How could I achieve the desired result ?
Thanks in advance, Sacha _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe