#2722: <<loop> when compiling with -O option with ghc-6.10.0.20081019
--------------------------------+-------------------------------------------
Reporter: uwe | Owner:
Type: bug | Status: new
Priority: normal | Milestone: Not GHC
Component: libraries (other) | Version: 7.0.1
Resolution: | Keywords: arrows
Testcase: | Blockedby:
Difficulty: Unknown | Os: Linux
Blocking: | Architecture: x86_64 (amd64)
Failure: Runtime crash |
--------------------------------+-------------------------------------------
Changes (by litoh):
* status: closed => new
* failure: => Runtime crash
* version: 6.10.1 => 7.0.1
* resolution: fixed =>
* architecture: x86 => x86_64 (amd64)
Comment:
I'm getting the same error with another Arrow library (FRP.Yampa). What's
strange though is that the error disappears under certain circumstances:
# use Bool instead of Event () for input type
# use Int instead of (String, Int) for output type
# -
# inline constant function
WTF? :)
{{{
{-# LANGUAGE Arrows #-}
module Main (main) where
import FRP.Yampa
type ObjIn = Event () -- loop #1
--type ObjIn = Bool -- no loop #1
type ObjOut = (String, Int) -- loop #2
--type ObjOut = Int -- no loop #2
type GameObj = SF ObjIn ObjOut
testObj :: GameObj
testObj = proc hit -> do
returnA -< ("testObj", 1) -- loop #2
-- returnA -< 1 -- no loop #2
process :: [GameObj] -> SF () [ObjOut]
process objs = proc _ -> do
rec
gamestate <- par logic objs
-< gamestate -- loop #3 (recursive definition!)
-- -< [] -- no loop #3
returnA -< gamestate
logic :: [ObjOut] -> [sf] -> [(ObjIn, sf)]
logic gamestate objs = map route objs
where
route obj =
(if null (foo gamestate) then NoEvent else NoEvent, obj) -- loop
#1
-- (if null (foo gamestate) then False else False, obj) -- no loop
#1
foo :: [ObjOut] -> [ObjOut]
foo [] = []
foo objs = concat (collisions objs)
where
collisions [] = []
collisions (out:objs') =
[[out, out'] | out' <- objs, out `collide` out'] -- loop #4
-- [[out, out'] | out' <- objs, True] -- no loop #4
collide :: ObjOut -> ObjOut -> Bool
collide (_, p) (_, p') = True -- loop #2
--collide p p' = True -- no loop #2
main :: IO ()
main = do
putStrLn . show $ embed (process [testObj]) ((), [(1.0, Nothing)])
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2722#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
