Compiler loops indefinitely on Morris-style fixed-point operator
Consider the following programs:
-- program 1.hs
newtype F a = F {unF :: F a -> a}
fix f = (\x -> f (unF x x)) (F (\x -> f (unF x x)))
fac = fix (\f -> \n -> if n == 0 then 1 else n * f (n - 1))
main = return ()
-- program 2: morris2.hs
newtype F a = F {unF :: F a -> a}
fix f = (\x -> f (unF x x)) (F (\x -> f (unF x x)))
fac = fix (\f -> \n -> if n == 0 then 1 else n * f (n - 1))
main = print (fac 2)
The first one compiles just fine; the second however causes GHC to go in an infinite loop:
$ ghc -c morris1.hs
$
$ ghc -c morris2.hs
(loops)
Trac metadata
Trac field | Value |
---|---|
Version | 6.4.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | low |
Resolution | Unresolved |
Component | Compiler (Type checker) |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | MacOS X |
Architecture | powerpc |