递归地将元组列表转换为列表元组

Question

I need a recursive function that returns a tuple of lists from a list of tuples. In other words, its type signature would be

func :: [(a,b)] -> ([a],[b])

Here is an example:

λ> func [(1,3), (2,4)]
([1,2], [3,4])

I made two functions to return a list of the first and second elements from the tuples and joining them, but I want only one recursive function to do it.

Answer 1

You're looking for unzip :

unzip :: [(a, b)] -> ([a], [b])

As general advice, when you know a type signature and you're wondering if there's any already-existing function that has that type signature, Hoogle is a good bet; searching for that type signature finds unzip as its first and only result.