Shimuuar

{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE OverlappingInstances  #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE UndecidableInstances #-}
module Region76 where

Shimuuar

import Data.Monoid

-- | Type class for monoidal accumulators
class Monoid m => Accumulator m a where
  -- | Convert value to 1-element accumulator
  unit :: a -> m
  unit a = cons a mempty
  -- | Prepend value to accumulator
  cons :: a -> m -> m
  cons a m = unit a <> m

Shimuuar

import Debug.Trace

xs1,xs2 :: [Int]
xs1 = map (\x -> (trace "2" 2 + trace "3" 3) * x) [0..]
xs2 = map (let y = trace "2" 2 + trace "3" 3 in \x -> x*y) [0..]
{-
*Main> take 4 xs1
[2
3
0,2

Shimuuar

import Data.Default
import Debug.Trace

data Proxy a = Proxy

class Magick a where
  magickStorage :: Proxy [a] -> String

instance Magick Int where
  magickStorage = const "Int"

Shimuuar

class Magic a where
  conjure :: String -> [a]
  magikStorage :: [a] -> String

-- Use return type
doMagik :: Magic a => Int -> [a]
doMagik n = concat $ replicate n res
  where
    res = conjure $ magikStorage res -- Must be lazy in res !!!!

Shimuuar

{-# LANGUAGE NoMonomorphismRestriction, BangPatterns #-}
module Main where

-- compile: ghc --make -main-is Prime.main Prime.hs -O2
-- $time ./Prime i 500000
-- ./Prime i 500000  4.35s user 0.00s system 99% cpu 4.453 total
-- ./Prime s 500000  7.69s user 0.03s system 99% cpu 7.726 total (!!!)
-- lookup OPT in comments about various optimization points

import System.Environment(getArgs)

Shimuuar

{-# LANGUAGE MultiParamTypeClasses  #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE FlexibleContexts       #-}
{-# LANGUAGE FlexibleInstances      #-}
{-# LANGUAGE UndecidableInstances   #-}
{-# LANGUAGE TypeOperators          #-}
{-# LANGUAGE DeriveDataTypeable     #-}
{-# LANGUAGE EmptyDataDecls         #-}

{-# LANGUAGE Rank2Types      #-}

Shimuuar

$ ghc --make foo
[1 of 1] Compiling Main             ( foo.hs, foo.o )
Linking foo ...
$ ./foo
"Starting IO"
Warning: Couldn't open "/dev/urandom"
Warning: using system clock for seed instead (quality will be lower)
"Starting IO"
foo: nonexitant: openFile: does not exist (No such file or directory)

Shimuuar

{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE OverlappingInstances  #-}
{-# LANGUAGE GADTs         #-}
{-# LANGUAGE TypeOperators #-}


-- Type constructor for list of types which is used in tests for
-- memberhip
data a ::: b

Shimuuar

import Criterion.Main   

----------------------------------------------------------------
-- Unit types

data U10 = 
     U10_01
   | U10_02
   | U10_03
   | U10_04