id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
322	fromInteger-related pattern match overlap warnings	ashley-y	simonpj	"{{{
The compiler incorrectly gives ""Warning: Pattern match(es) are 
overlapped"" for this file:

{-# OPTIONS -Werror #-}

module Buggy where

	instance (Num a) => Num (Maybe a) where
		(Just a) + (Just b) = Just (a + b)
		_ + _ = Nothing
		(Just a) - (Just b) = Just (a - b)
		_ - _ = Nothing
		(Just a) * (Just b) = Just (a * b)
		_ * _ = Nothing
		negate (Just a) = Just (negate a)
		negate _ = Nothing
		abs (Just a) = Just (abs a)
		abs _ = Nothing
		signum (Just a) = Just (signum a)
		signum _ = Nothing
		fromInteger = Just . fromInteger

	f :: Maybe Int -> Int
	f 1 = 1
	f Nothing = 2
	f _ = 3

}}}"	bug	new	normal	_|_	Compiler	6.4	None	warnings		Unknown/Multiple	Unknown/Multiple	None/Unknown	Unknown	ds060