[project @ 1997-07-31 00:05:10 by sof]

[ghc-hetmet.git] / ghc / compiler / tests / typecheck / should_succeed / tc086.hs

diff --git a/ghc/compiler/tests/typecheck/should_succeed/tc086.hs b/ghc/compiler/tests/typecheck/should_succeed/tc086.hs
deleted file mode 100644 (file)
index 4d9ba6e..0000000
--- a/ghc/compiler/tests/typecheck/should_succeed/tc086.hs
+++ /dev/null
@@ -1,60 +0,0 @@
-{-
-  From: Marc van Dongen <dongen@cs.ucc.ie>
-  Date: Sat, 31 May 1997 19:57:46 +0100 (BST)
-
-   panic! (the `impossible' happened):
-           tcLookupTyVar:a_r6F
-
-   Please report it as a compiler bug to glasgow-haskell-bugs@dcs.gla.ac.uk.
-
-
-If the instance definition for (*) at the end of this toy module
-is replaced by the definition that is commented, this all compiles
-fine. Strange, because the two implementations are equivalent modulo
-the theory {(*) = multiply}.
-
-Remove the `multiply :: a -> a -> a' part, and it compiles without
-problems.
-
-
-SPJ note: the type signature on "multiply" should be
-       multiply :: Group a => a -> a -> a
-
--}
-
-module Rings( Group, Ring ) where
-
-import qualified Prelude( Ord(..), Eq(..), Num(..) )
-import Prelude hiding( Ord(..), Eq(..), Num(..), MonadZero( zero ) )
-
-class Group a where
-  compare     :: a -> a -> Prelude.Ordering
-  fromInteger :: Integer -> a
-  (+) :: a -> a -> a
-  (-) :: a -> a -> a
-  zero :: a
-  one  :: a
-  zero = fromInteger 0
-  one  = fromInteger 1
-
--- class (Group a) => Ring a where
--- (*) :: a -> a -> a
--- (*) a b =
---                  case (compare a zero) of
---                    EQ -> zero
---                    LT -> zero - ((*) (zero - a) b)
---                    GT -> case compare a one of
---                            EQ -> b
---                            _  -> b + ((*) (a - one) b)
-
-class (Group a) => Ring a where
-  (*) :: a -> a -> a
-  (*) a b = multiply a b
-          where multiply :: Group a => a -> a ->a 
-                multiply a b
-                  = case (compare a zero) of
-                      EQ -> zero
-                      LT -> zero - (multiply (zero - a) b)
-                      GT -> case compare a one of
-                              EQ -> b
-                              _  -> b + (multiply (a - one) b)