gistfile1.txt

collatz :: Integer -> Maybe Integer
collatz n
    | n < 1 = Nothing
    | n == 1 = Just 0
    | even n = fmap (+ 1) $ collatz (n `div` 2)
    | odd n = fmap (+ 1) $ collatz (3 * n + 1)

gistfile2.txt

    Pattern match(es) are non-exhaustive
    In an equation for ‘collatz’:
        Patterns not matched:
            GHC.Num.Integer.IS _
            GHC.Num.Integer.IP _
            GHC.Num.Integer.IN _

package.yaml

name: collatz-conjecture
version: 1.2.1.4

dependencies:
  - base

library:
  exposed-modules: CollatzConjecture
  source-dirs: src
  ghc-options: -Wall
  # dependencies:
  # - foo       # List here the packages you
  # - bar       # want to use in your solution.

tests:
  test:
    main: Tests.hs
    source-dirs: test
    dependencies:
      - collatz-conjecture
      - hspec