{-# OPTIONS_GHC -Wall -fno-warn-name-shadowing #-}

module Main where

import Control.Monad.Par.Scheds.Trace
  -- gives slightly better results than Control.Monad.Par with monad-par-0.3.4

import System.Environment

test :: Int -> Int -> Par Int           
test n m = do
             i <- new                -- create an IVar
             j <- new                -- create an IVar
             fork (put i (fib n))    -- start a parallel task
             fork (put j (fib m))    -- start a parallel task
             a <- get i              -- get the result (when available)
             b <- get j              -- get the result (when available)
             return (a+b)            -- return the result


fib :: Int -> Int
fib 0 = 1
fib 1 = 1
fib n = nf1+nf2+1
        where nf1 = fib (n-1)
              nf2 = fib (n-2)
          

pfib :: Int -> Par Int
pfib n | n<=1 = return 1  -- do { resv <- new; put resv 1 ; return resv }
pfib n | otherwise =
         do
              nv1 <- spawn (pfib (n-1))     -- start a parallel task
              nv2 <- spawn (pfib (n-2))     -- start a parallel task
              nf1 <- get nv1                -- get the result (when available)
              nf2 <- get nv2                -- get the result (when available)
              return (nf1+nf2+1)
	
main = do args <- getArgs
          let 
            n = read (args!!0) :: Int
            m = read (args!!1) :: Int
          putStr ("Running a test of: fib " ++ (show n) ++ " + fib " ++ (show m) ++ " = ")
          let res = runPar $ test m n
          putStrLn (show res)