HackerRankSolutions

Main.hs

-- Input: 10
-- Output: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]

-- Signature
fn :: (Integral a) => a -> [a]
-- Solution with pattern-matching
fn 0x0 = []
fn n = if n - 1 < 0 then fn 0 else fn (n - 1) ++ [n]

-- n = -1
-- fn = fn(-1 -1 ? 0 : n-1) ++ [-1]
-- fn = [] ++ [-1]
-- fn = [-1]

-- n = 2 -> fn(2 - 1) ++ [2]

main = do
  n <- readLn :: IO Int
  print (fn n)