hashExpr e = fromIntegral (hash_expr (1,emptyVarEnv) e .&. 0x7fffffff)
-- UniqFM doesn't like negative Ints
-type HashEnv = (Int, VarEnv Int) -- ^ Hash code for bound variables
+type HashEnv = (Int, VarEnv Int) -- Hash code for bound variables
hash_expr :: HashEnv -> CoreExpr -> Word32
-- Word32, because we're expecting overflows here, and overflowing