* John Hughes <[EMAIL PROTECTED]> [2001-01-22T20:10+0100]:
> liam@HEMPC ~/BDDs
> $ ghc -static -c -fglasgow-exts Pigeon.hs
[...]
> basicTypes/Var.lhs:194: Non-exhaustive patterns in function
> readMutTyVar
This is a nice one. If you change it in a sublte way:
+++ Pigeon.hi
pigeon n t =
- do a<-at 1
+ do a<-at
orBDD t a a
- where at i = varBDD t 0
+ where at = varBDD t 0
it compiles, but GHC emits:
zonkIdOcc: FunDep_aMr
zonkIdOcc: FunDep_aMr
This leads to Imperative.hi, in which you are using Functional
Dependencies, obviously. While I don't know jack about them, I
remember them causing some glitches in GHC (which might already be
solved in CVS). However, I edited the FD away in Imperative.hi and
Pigeon.hs compiled (even your original version).
+++ Imperative.hi
-1 class {PrelBase.Monad m} => Imperative s m :: (* -> *) | m -> s where {st ::
__forall [a] => PrelST.ST s a -> m a} ;
+1 class {PrelBase.Monad m} => Imperative s m :: (* -> *) where {st :: __forall [a]
+=> PrelST.ST s a -> m a} ;
> There is no file Var.lhs on my machine: I assume it's part of the
> source of GHC.
yes. <fptools>/ghc/compiler/basicTypes/Var.lhs
> What's the behaviour that is wrong, in my opinion? Well, firstly (and
> mainly) that the compiler rejects the program at all. Secondly that
> the error message refers to a non-existent source file. And thirdly,
> since when have non-exhaustive patterns been an error? That's about
> it!
internal compiler error =) Maybe someone should mark them in a more
obvious way...
> Grateful for help -- it would be fun to see how much speedup I get
> from GHC...!
Want to beat SMV/BMC? =)
Cheers,
M/
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