[Haskell-cafe] Num instances for 2-dimensional types
shahn at cs.tu-berlin.de
Mon Oct 5 08:40:31 EDT 2009
I often stumble upon 2- (or 3-) dimensional numerical data types like
or similar self defined ones. I like the idea of creating instances for Num for
these types. The meaning of (+), (-) and negate is clear and very intuitive, i
think. I don't feel sure about (*), abs, signum and fromInteger. I used to
fromInteger n = (r, r) where r = fromInteger n
, but thinking about it,
fromInteger n = (fromInteger n, 0)
seems very reasonable, too.
Any thoughts on that? How would you do it?
btw: These are two examples i looked at in hackage:
Data.Complex.Complex (which is special, cause it is mathematically defined,
what (*), abs, signum and fromInteger should do (i think))
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