-- Gabe Schoenbach

-- | A module for learning about ADTs

module ADT where

  import Prelude

  -- Exercise 3.1

  -- | The collatz function defined with guards and then with if/then/else

  collatz :: Integral n => n -> n
  collatz n
    | n == 1    = 1
    | even n    = 1 + collatz (n `div` 2)
    | otherwise = 1 + collatz (3*n + 1)

  collatz' :: Integral n => n -> n
  collatz' n = if n == 1
               then 1
               else if even n
                    then 1 + collatz' (n `div` 2)
                    else 1 + collatz' (3*n + 1)