{-# LANGUAGE DeriveGeneric #-}
{-# OPTIONS_GHC -Wall -O2 #-}
module Main ( main ) where

import Criterion
import Criterion.Main
import Data.Hashable
import Data.Hashable.Generic
import GHC.Generics

data HandRolled = HR0
                | HR1 (Maybe Int)
                | HR2 HandRolled HandRolled

data GenericRolled = GR0
                   | GR1 (Maybe Int)
                   | GR2 GenericRolled GenericRolled
    deriving Generic

instance Hashable HandRolled where
    hashWithSalt salt HR0       = hashWithSalt salt $ (Left () :: Either () ())
    hashWithSalt salt (HR1 mi)  = hashWithSalt salt $ (Right $ Left mi :: Either () (Either (Maybe Int) ()))
    hashWithSalt salt (HR2 x y) = hashWithSalt salt $ (Right $ Right (x, y) :: Either () (Either () (HandRolled, HandRolled)))

instance Hashable GenericRolled where
    hashWithSalt s x = gHashWithSalt s x

bigHandRolledDS :: HandRolled
bigHandRolledDS = let a = HR0
                      b = HR1 $ Just 1
                      c = HR1 $ Nothing
                      d = HR1 $ Just 3
                      e = HR2 a b
                      f = HR2 c d
                      g = HR2 e e
                      h = HR2 f f
                      i = HR2 e f
                      j = HR2 g h
                      k = HR2 i j
                      l = HR2 k k
                      m = HR2 l l
                      n = HR2 m m
                      o = HR2 n n
                      p = HR2 o o
                      q = HR2 p p
                      r = HR2 q q
                      s = HR2 r r
                      t = HR2 s s
                      u = HR2 t t
                      v = HR2 u u
                      w = HR2 v v
                      x = HR2 w w
                      y = HR2 x x
                      z = HR2 y y
                      za = HR2 z z
                      zb = HR2 za za
                      zc = HR2 zb zb
                      zd = HR2 zc zc
                      ze = HR2 zd zd
                   in ze

bigGenericRolledDS :: GenericRolled
bigGenericRolledDS = f bigHandRolledDS
    where
        f HR0       = GR0
        f (HR1 x)   = GR1 x
        f (HR2 x y) = GR2 (f x) (f y)

main :: IO ()
main = defaultMain [ bcompare [ bench "handrolled" $ whnf hash bigHandRolledDS
                              , bench "generic" $ whnf hash bigGenericRolledDS
                              ]
                   ]