Open TGOlson opened 9 years ago
https://hackage.haskell.org/package/base-4.7.0.1/docs/Data-Monoid.html
mappend mempty x = x mappend x mempty = x mappend x (mappend y z) = mappend (mappend x y) z mconcat = foldr mappend mempty
That's a great idea~
https://hackage.haskell.org/package/base-4.7.0.1/docs/Data-Monoid.html