Re: Yet another External Core bug
On Fri, Jan 24, 2003 at 01:31:46PM -, Simon Peyton-Jones wrote: In short, it's really a bug, but not a particularly easy one to fix. Rumination required. But it probably only happens on a few programs, right? It happens on at least two of the nofib benchmarks, so it seems to be pretty significant. I didn't understand your explanation of the problem, so unfortunately I can't suggest any solution. Did the other Core bug I reported at the same time http://www.haskell.org/pipermail/glasgow-haskell-bugs/2003-January/002877.html ever get fixed? Thanks, Kirsten -- Kirsten Chevalier * [EMAIL PROTECTED] * Often in error, never in doubt ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
RE: Yet another External Core bug
| The attached file (generated by running ghc -fext-core on the Fibheaps | benchmark from the nofib suite) fails to typecheck: | | $ ghc -dcore-lint Fibheaps.hcr | | Couldn't match `#' against `*' | Expected kind: # | Inferred kind: * | When checking kinds in `GHC.Prim.(-) (GHC.Prim.State# s)' I've found what's going on here. Here is the comment from the definition of the type constructor for (-): funTyCon = mkFunTyCon funTyConName (mkArrowKinds [liftedTypeKind, liftedTypeKind] liftedTypeKind) -- You might think that (-) should have type (? - ? - *), and you'd be right -- But if we do that we get kind errors when saying -- instance Control.Arrow (-) -- becuase the expected kind is (*-*-*). The trouble is that the -- expected/actual stuff in the unifier does not go contra-variant, whereas -- the kind sub-typing does. Sigh. It really only matters if you use (-) in -- a prefix way, thus: (-) Int# Int#. And this is unusual. In short, it's really a bug, but not a particularly easy one to fix. Rumination required. But it probably only happens on a few programs, right? S ___ Glasgow-haskell-bugs mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
