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takoeight0821/Group.hs

Created June 5, 2015 10:12
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Group.hs
import Data.Monoid
class Group g where
gidentity :: g
gop :: g -> g -> g
ginverse :: g -> g
instance Num a => Group (Sum a) where
gidentity = Sum 0
(Sum x) `gop` (Sum y) = Sum (x + y)
ginverse (Sum a) = Sum (negate a)
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