I think that's just because you are used to see it used that way. And it's not like CoffeeScript invented this. Haskell does it: \x -> x + 1 OCaml does i

I think that's just because you are used to see it used that way. And it's not like CoffeeScript invented this. Haskell does it: \x -> x + 1 OCaml does it: fun (x : int) -> x + 1 It is very common in functional languages to use -> both for function bodies and return types.