# Benchmarking pure/effectful computations

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a year ago

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import Data.Time (Time, diff) import Data.Time.Duration (Milliseconds) import Effect (Effect) import Effect.Class.Console (log) import Effect.Now (nowTime) -- | Fibonacci as a pure function fib :: Int -> Int fib 0 = 0 fib 1 = 1 fib n = fib (n-1) + fib (n-2) diff' :: Time -> Time -> Milliseconds diff' t2 t1 = diff t2 t1 :: Milliseconds -- | Benchmarking Fibonacci, where we let-bind its result benchFibLetBind :: Int -> Effect Int benchFibLetBind n = do t1 <- nowTime let m = fib n -- If `m` is not yet used t2 <- nowTime log (show (diff' t2 t1) <> "ms") -- prints 0.0 ms pure m -- | Benchmarking Fibonacci, where we let-bind its result and log it benchFibLetBindPrint :: Int -> Effect Int benchFibLetBindPrint n = do t1 <- nowTime let m = fib n -- If `m` is subsequently printed log (show m) t2 <- nowTime log (show (diff' t2 t1) <> "ms") -- prints correct ms pure m -- | Benchmarking Fibonacci, where we monadically bind its result (using `pure`) benchFibDoBind :: Int -> Effect Int benchFibDoBind n = do t1 <- nowTime m <- pure $ fib n -- If `fib` is wrapped in `pure`, and the result `m` is not yet used t2 <- nowTime log (show (diff' t2 t1) <> "ms") -- prints 0.0 ms pure m -- | Benchmarking Fibonacci, where we monadically bind its result (using `pure`) and log it benchFibDoBindPrint :: Int -> Effect Int benchFibDoBindPrint n = do t1 <- nowTime m <- pure $ fib n -- If `fib` is wrapped in `pure`, and the result `m` is subsequently printed log (show m) t2 <- nowTime log (show (diff' t2 t1) <> "ms") -- prints correct ms pure m -- | Fibonacci as an effectful function fibm :: Int -> Effect Int fibm 0 = pure 0 fibm 1 = pure 1 fibm n = do n1 <- fibm (n-1) n2 <- fibm (n-2) pure (n1 + n2) -- | Benchmarking the effectful version of Fibonacci, where we monadically bind its result benchFibmBind :: Int -> Effect Int benchFibmBind n = do t1 <- nowTime m <- fibm n -- If `fib` itself is defined as an effectful computation `fibm` t2 <- nowTime log (show (diff t2 t1 :: Milliseconds) <> "ms") -- prints correct ms (without needing the result `m` to be used beforehand) pure m benchFibs :: Effect Unit benchFibs = do log ("-- | Benchmarking Fibonacci, where we let-bind its result") _ <- benchFibLetBind 40 log ("-- | Benchmarking Fibonacci, where we let-bind its result and log it") _ <- benchFibLetBindPrint 40 log ("-- | Benchmarking Fibonacci, where we monadically bind its result (using `pure`)") _ <- benchFibDoBind 40 log ("-- | Benchmarking Fibonacci, where we monadically bind its result (using `pure`) and log it") _ <- benchFibDoBindPrint 40 log ("-- | Benchmarking the effectful version of Fibonacci, where we monadically bind its result") _ <- benchFibmBind 40 pure unit