3 ms·

If you type foldr instead of foldl it won't complain.

• tikhonj 15y ago
  In most cases it will because they have different types: foldl :: (a -> b -> a) -> a -> [b] -> a foldr :: (a -> b -> b) -> b -> [a] -> b So the only time it will be the same is if a and b are the same type.
  • deleted 15y ago
    [deleted]
  • jlarocco 15y ago
    > So the only time it will be the same is if a and b are the same type. Which they will be in most of the example code he used. They're not the best examples.