#1376: panic caused in ghci by the following code involving monad transformers
-------------------------------------+--------------------------------------
Reporter: [EMAIL PROTECTED] | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.6.1
Severity: normal | Keywords:
Difficulty: Unknown | Os: MacOS X
Testcase: | Architecture: powerpc
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I was attempting to learn to use monad transformers when I came across
this bug,
the following is the contents of StateAccum.hs
{{{
import Control.Monad
import Control.Monad.State
import Control.Monad.List
sumUp :: [Int] -> State Int [()]
sumUp = sequence . map (modify . (+))
type StateWithList = ListT (State Int)
sumUp' xs = do x <- xs
lift (modify (+x))
return (lift get)
sumThreeLists :: [Int] -> [Int] -> [Int] -> Int
sumThreeLists xs ys zs = execState (sumUp xs >> sumUp ys >> sumUp zs) 0
main = do print $ execState (sumUp [1,2,3]) 0
print $ sumThreeLists [1..10] [1..10] [1..10]
}}}
This is a transcript of the ghci session that causes the panic:
{{{
% ghci StateAccum.hs
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6.1, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Loading package base ... linking ... done.
[1 of 1] Compiling Main ( StateAccum.hs, interpreted )
Ok, modules loaded: Main.
*Main> sumUp' [return 1, return 2]
ghc-6.6.1: panic! (the 'impossible' happened)
(GHC version 6.6.1 for powerpc-apple-darwin):
nameModule it{v a1es}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
*Main>
}}}
I'm using the binary ghc package for Mac OS PPC provided on the ghc site.
The output for uname -a on my machine is
{{{ Darwin Logan-Capaldos-Computer.local 8.9.0 Darwin Kernel Version
8.9.0: Thu Feb 22 20:54:07 PST 2007; root:xnu-792.17.14~1/RELEASE_PPC
Power Macintosh powerpc }}}
Running with ghci -v, this is the output
{{{
% ghci -v StateAccum.hs
___ ___ _
/ _ \ /\ /\/ __(_)
/ /_\// /_/ / / | | GHC Interactive, version 6.6.1, for Haskell 98.
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
\____/\/ /_/\____/|_| Type :? for help.
Using package config file: /usr/local/lib/ghc-6.6.1/package.conf
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
Hsc static flags: -static
Loading package base ... linking ... done.
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
wired-in package base mapped to base-2.1.1
wired-in package rts mapped to rts-1.0
wired-in package haskell98 mapped to haskell98-1.0
wired-in package template-haskell mapped to template-haskell-2.1
*** Chasing dependencies:
Stable obj: []
Stable BCO: []
unload: retaining objs []
unload: retaining bcos []
Upsweep completely successful.
*** Deleting temp files:
Deleting:
*** Chasing dependencies:
Stable obj: []
Stable BCO: []
unload: retaining objs []
unload: retaining bcos []
compile: input file StateAccum.hs
*** Checking old interface for main:Main:
[1 of 1] Compiling Main ( StateAccum.hs, interpreted )
*** Parser:
*** Renamer/typechecker:
*** Desugar:
Result size = 244
*** Simplify:
Result size = 292
Result size = 263
Result size = 263
*** Tidy Core:
Result size = 263
*** CorePrep:
Result size = 331
*** ByteCodeGen:
*** Deleting temp files:
Deleting:
Upsweep completely successful.
*** Deleting temp files:
Deleting:
Ok, modules loaded: Main.
*Main> sumUp' [return 1, return 2]
*** Parser:
*** Desugar:
*** Simplify:
*** CorePrep:
*** ByteCodeGen:
ghc-6.6.1: panic! (the 'impossible' happened)
(GHC version 6.6.1 for powerpc-apple-darwin):
nameModule it{v a1es}
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
*Main>
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/1376>
GHC <http://www.haskell.org/ghc/>
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