Problem with Monoid instance of Data.Map
See..
http://www.haskell.org/pipermail/libraries/2007-May/007491.html
Data.Map Monoid instance is currently..
instance (Ord k) => Monoid (Map k v) where
mempty = empty
mappend = union
mconcat = unions
- .but probably should be..
instance (Ord k, Monoid v) => Monoid (Map k v) where
mempty = empty
mappend map0 map1 = unionWith mappend map0 map1
mconcat maps = foldr (unionWith mappend) empty maps
Adrian Hey
Trac metadata
Trac field | Value |
---|---|
Version | 6.6.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | libraries/base |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | Multiple |
Architecture | Multiple |