Eq instance for (a,b,c,d,e) and upwards



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Martin Norbäck (d95mback@dtek.chalmers.se)
Thu, 19 Apr 2001 16:15:14 +0200


I am trying to compile a program which uses equality between 5-tuples. I know I probably should define my own data type and derive equality on that, but as it is now, I use a 5-tuple. For some reason nhc98 only defines equality for tuples up to 4. I can work around this by defining the equality myself: instance (Eq a,Eq b,Eq c,Eq d,Eq e) => Eq (a,b,c,d,e) where (a,b,c,d,e) == (a',b',c',d',e') = a == a' && b == b' && c == c' && d == d' && e == e' but then both ghc and hugs complains about a duplicate instance declaration, and I really want to write portable code. I don't know what the standard says about this, but this is not listed as a deficiency in http://www.cs.york.ac.uk/fp/nhc98/98.html Is there a way to fix this in nhc98? n. -- [ http://www.dtek.chalmers.se/~d95mback/ ] [ PGP: 0x453504F1 ] [ UIN: 4439498 ] Opinions expressed above are mine, and not those of my future employees. SIGBORE: Signature boring error, core dumped


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