Bugs with fundeps

[Simon Peyton-Jones]

All three were caused by a bug in the context reducer. 
It'll be fixed as soon as I can conmit it.  Thanks; keep
hammering it.

Simon

| -----Original Message-----
| From: Marcin 'Qrczak' Kowalczyk [mailto:qrczak@knm.org.pl]
| Sent: 02 February 2001 21:02
| To: cvs-ghc@haskell.org
| Subject: Bugs with fundeps
| 
| 
| The first program let ghc -fglasgow-exts go into infinite 
| loop printing
| tcGetTyVar e{-a2145-}.
| 
| The second gives an error message about ambiguous type 
| variable. Should
| it be an error? It was not an error before.
| 
| The third causes panic.
| 
| --------------------------------------------------------------
| ----------
| module Bug1 where
| 
| class Foo r a | r -> a where
|     foo :: a -> r
| 
| instance Foo (Maybe e) e where
|     foo = Just
| 
| bad:: Num e => Maybe e
| bad = foo 0
| --------------------------------------------------------------
| ----------
| module Bug2 where
| 
| class Foo r a | r -> a where
|     foo :: r -> a
| 
| instance Foo [m a] (m a)
| 
| bad:: Monad m => m a
| bad = foo bar
| 
| bar:: Monad m => [m a]
| bar = []
| --------------------------------------------------------------
| ----------
| module Bug3 where
| 
| class Foo r a | r -> a where
|     foo :: r -> a
| 
| instance Foo [m a] (m a)
| 
| bad:: Monad m => m a
| bad = foo bar
| 
| bar:: [m a]
| bar = []
| --------------------------------------------------------------
| ----------
| 
| -- 
|  __("<  Marcin Kowalczyk * qrczak@knm.org.pl http://qrczak.ids.net.pl/
|  \__/
|   ^^                      SYGNATURA ZASTEPCZA
| QRCZAK
| 
| 
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