File: simplrun002.hs

package info (click to toggle)
ghc-cvs 20040725-2
  • links: PTS
  • area: main
  • in suites: sarge
  • size: 68,484 kB
  • ctags: 19,658
  • sloc: haskell: 251,945; ansic: 109,709; asm: 24,961; sh: 12,825; perl: 5,786; makefile: 5,334; xml: 3,884; python: 682; yacc: 650; lisp: 477; cpp: 337; ml: 76; fortran: 24; csh: 18
file content (24 lines) | stat: -rw-r--r-- 627 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
 
{-# OPTIONS -fglasgow-exts #-}

-- !!! A rules test
-- At one time the rule got too specialised a type:
--
--  _R "ffoo" forall {@ a1 v :: (a1, ((), ()))} 
--	      fst @ a1 @ () (sndSnd @ a1 @ () @ () v) = fst @ a1 @ ((), ()) v


module Main where

import IO
import System.IO.Unsafe ( unsafePerformIO )

{-# NOINLINE [0] sndSnd #-}
-- Dont inline till last, to give the rule a chance
sndSnd (a,(b,c)) = (a,c)

trace x y = unsafePerformIO (hPutStr stderr x >> hPutStr stderr "\n" >> return y)

{-# RULES "foo" forall v .  fst (sndSnd v) = trace "Yes" (fst v) #-}

main :: IO ()
main = print (fst (sndSnd (True, (False,True))))