A complex implementation of integer to binary conversion in Haskell

00_ToBinary.hs

import Data.Bits (Bits (testBit), FiniteBits(countLeadingZeros, finiteBitSize))
import Data.Char (intToDigit)

toBinary :: FiniteBits a => a -> [Char]
toBinary n = [charOfBitAt i n | i <- reverse [0..(bitLength n - 1)]]
    where
        bitLength = (-) <$> finiteBitSize <*> countLeadingZeros
        charOfBitAt i = intToDigit . fromEnum . flip testBit i

01_Example.hs

import Control.Monad (forM_)
import Text.Printf (printf)

example :: IO ()
example = forM_ [(0 :: Int)..20] $ \n -> printf "%2d -> %s\n" n (show $ toBinary n)