PureScript by Example - 5.5 Guards - Exercise 1-2 Solutions

Guards.purs

module Guards where

import Prelude

-- Exercise 1
factorial :: Int -> Int
factorial 0 = 1
factorial n = n * factorial (n - 1)

-- Exercise 2
choose :: Int -> Int -> Int
choose _ 0 = 1
choose n k
  | n == k    = 1
  | otherwise = choose (n - 1) k + choose (n - 1) (k - 1)