tcfail073.hs:3:
    Duplicate or overlapping instance declarations
	for `Eq (a, b)' at PrelTup.hi:11 and tcfail073.hs:8
 
tcfail073.hs:8:
    Could not deduce `Eq a'
	(arising from use of `==' at tcfail073.hs:8)
	from the context (Eq (a, b), /= at (a, b), == at (a, b))
    Probable cause: missing `Eq a' in instance declaration context
    When checking the methods of an instance declaration


Compilation had errors