A fragment of an attempt to make pairs serve as complex numbers,
using ghc/hugs extensions:
instance Num a => Num (a,a) where
(x,y) * (u,v) = (x*u-y*v, x*v+y*u)
Unfortunately, type inference isn't strong enough to cope with
(1,1)*(1,1)
Why shouldn't it be strengthened to do so?
Or is there a declarative trick (perhaps with dependent
classes) that will accomplish the goal?
Doug McIlroy
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