#3964: Impossible happened when using ViewPattern in Arrows
-------------------------------+--------------------------------------------
Reporter: uzytkownik | Owner: simonpj
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.1
Keywords: | Difficulty:
Os: Linux | Testcase:
Architecture: x86_64 (amd64) | Failure: Compile-time crash
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Description changed by igloo:
Old description:
> When I try to load file in ghci impossible happened:
>
> ghc: panic! (the 'impossible' happened)
> (GHC version 6.12.1 for x86_64-unknown-linux):
> collectl/go
> ((=={v aOp} [lid]
> u{v avw} [lid]) -> {229:56-59}{229:56-59}ghc-prim:GHC.Bool.True{(w)
> d 6u})
>
> Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
>
> Problematic function:
> isOn :: ArrowChoice a => DSignal a c -> SF a b (Maybe c)
> isOn (DSignal _ f u) = let sf = SF $! \_ -> proc (_, s, e) ->
> case fromDynamic (_payload e) of
> Just (Event ((== u) -> True) v) ->
> returnA -< (Just (f v), s, sf)
> Nothing -> returnA -< (Nothing, s, sf)
> in sf
>
> (Full sources will be attached. As it was found in-development so style
> may not be perfect)
New description:
When I try to load file in ghci impossible happened:
{{{
ghc: panic! (the 'impossible' happened)
(GHC version 6.12.1 for x86_64-unknown-linux):
collectl/go
((=={v aOp} [lid]
u{v avw} [lid]) -> {229:56-59}{229:56-59}ghc-prim:GHC.Bool.True{(w)
d 6u})
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}}
Problematic function:
{{{
isOn :: ArrowChoice a => DSignal a c -> SF a b (Maybe c)
isOn (DSignal _ f u) = let sf = SF $! \_ -> proc (_, s, e) ->
case fromDynamic (_payload e) of
Just (Event ((== u) -> True) v) ->
returnA -< (Just (f v), s, sf)
Nothing -> returnA -< (Nothing, s, sf)
in sf
}}}
(Full sources will be attached. As it was found in-development so style
may not be perfect)
--
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3964#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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