alt Hacker NewsIn other words, look at the types. The type of the folding function (the first argument) indicates how each fold works.
foldl' :: Foldable t => (b -> a -> b) -> b -> t a -> b
foldr :: Foldable t => (a -> b -> b) -> b -> t a -> bIn other words, look at the types. The type of the folding function (the first argument) indicates how each fold works.
foldl' :: Foldable t => (b -> a -> b) -> b -> t a -> b
foldr :: Foldable t => (a -> b -> b) -> b -> t a -> b
That's what I tend to do, but since foldr/foldl' is so ubiquitous in Haskell it would be nice if I could just remember the argument order of the callback. kccqzy's explanation (in particular "it replaces the comma") might just help me do that :)