1 Nov
2016
1 Nov
'16
11:55 a.m.
sum a tuple of monoids
here is something, not quite what you are looking for, but close: Monoid http://hackage.haskell.org/package/base-4.9.0.0/docs/Data-Monoid.html#t:Mono... a => Monoid http://hackage.haskell.org/package/base-4.9.0.0/docs/Data-Monoid.html#t:Mono... (Maybe http://hackage.haskell.org/package/base-4.9.0.0/docs/Data-Maybe.html#t:Maybe a) (Monoid http://hackage.haskell.org/package/base-4.9.0.0/docs/Data-Monoid.html#t:Mono... a, Monoid http://hackage.haskell.org/package/base-4.9.0.0/docs/Data-Monoid.html#t:Mono... b) => Monoid http://hackage.haskell.org/package/base-4.9.0.0/docs/Data-Monoid.html#t:Mono... (a, b) mappend (Just [1], Just [2,3]) (Nothing, Just [5])::(Maybe [Int],Maybe [Int]) (Just [1],Just [2,3,5])