Timer.hs

{-# LANGUAGE BangPatterns #-}

module Timer
  ( timer
  , timer_
  ) where

import           Data.Time

timer :: IO a -> IO a
timer a = do
  start <- getCurrentTime
  !result <- a
  end <- getCurrentTime
  print (diffUTCTime end start)
  return result

timer_ :: a -> IO a
timer_ a = timer $ return a

-- *Main Lib> timer $ print 42
-- 42
-- 0.000044s

-- *Main Lib > timer_ $ last [1..100000000]
-- 2.171535s
-- 100000000

-- *Main Lib Timer Control.Concurrent> timer $ threadDelay 2000000
-- 2.00183s