Reorganisation of the source tree

[ghc-hetmet.git] / compiler / ilxGen / tests / test11.hs

diff --git a/compiler/ilxGen/tests/test11.hs b/compiler/ilxGen/tests/test11.hs
new file mode 100644 (file)
index 0000000..ce53f71
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+++ b/compiler/ilxGen/tests/test11.hs
@@ -0,0 +1,61 @@
+{-# OPTIONS -fglasgow-exts #-}
+
+import PrelGHC
+
+class  EEq a  where
+    (===), (/==)               :: a -> a -> Bool
+
+--    x /= y           = not (x == y)
+--    x == y           = not (x /= y)
+--    x /= y           =  True
+    (/==) x y            = mynot  ((===) x y)
+    x === y            =  True
+
+data EOrdering = ELT | EEQ | EGT 
+
+mynot True = False
+mynot False = True
+
+{-
+class  (EEq a) => EOrd a  where
+    ecompare             :: a -> a -> EOrdering
+    (<<), (<<=), (>>>=), (>>>):: a -> a -> Bool
+    emax, emin         :: a -> a -> a
+
+-- An instance of Ord should define either compare or <=
+-- Using compare can be more efficient for complex types.
+    ecompare x y
+           | x === y    = EEQ
+           | x <<= y    = ELT  -- NB: must be '<=' not '<' to validate the
+                               -- above claim about the minimal things that can
+                               -- be defined for an instance of Ord
+           | otherwise = EGT
+
+    x <<= y  = case ecompare x y of { EGT -> False; _other -> True }
+    x <<        y  = case ecompare x y of { ELT -> True;  _other -> False }
+    x >>>= y  = case ecompare x y of { ELT -> False; _other -> True }
+    x >>>       y  = case ecompare x y of { EGT -> True;  _other -> False }
+
+       -- These two default methods use '>' rather than compare
+       -- because the latter is often more expensive
+    emax x y = if x >>> y then x else y
+    emin x y = if x >>> y then y else x
+-}
+
+data EInt = EI Int#
+
+ezeroInt, eoneInt, etwoInt, emaxInt, eminInt :: EInt
+ezeroInt = EI 0#
+eoneInt  = EI 1#
+etwoInt  = EI 2#
+eminInt  = EI (-2147483648#)   -- GHC <= 2.09 had this at -2147483647
+emaxInt  = EI 2147483647#
+eeqInt (EI x) (EI y) = x ==# y
+eneInt (EI x) (EI y) = x /=# y
+
+instance EEq EInt where
+    (===) x y = x `eeqInt` y
+    (/==) x y = x `eneInt` y
+
+main = putStr (if (ezeroInt === eoneInt) then "no!\n" else "yes!\n")
+