お試し with unboxed-ref inspired by https://qiita.com/mod_poppo/items/03fc14f693b601e0a00f

StateVSIORef.hs

{-# LANGUAGE LambdaCase #-}

module Bench.StateVSIORef where

import Data.IORef
import Data.IORef.Unboxed
import Control.Monad.State.Strict


n :: Int
n = 2 ^ (30 :: Int)

type Acc = Int

f :: Int -> Acc -> Acc
f i acc = acc + (i `rem` 3)

e :: Acc
e = 0

someCalculationWithState :: IO Acc
someCalculationWithState = flip evalStateT e $ do
  forM_ [0..n] $ \i -> do
    modify' (f i)
  get

someCalculationWithIORef :: IO Acc
someCalculationWithIORef = do
  accRef <- newIORef e
  forM_ [0..n] $ \i -> do
    modifyIORef' accRef (f i)
  readIORef accRef

someCalculationWithIORefU :: IO Acc
someCalculationWithIORefU = do
  accRef <- newIORefU e
  forM_ [0..n] $ \i -> do
    modifyIORefU accRef (f i)
  readIORefU accRef

someCalculationWithRec :: IO Acc
someCalculationWithRec = return $ loop 0 e
  where
    loop i acc
      | i == n    = f i acc
      | otherwise = loop (i + 1) $ f i acc