IntMap intersectionWith type is too restrictive

Scott Dillard sedillard at
Fri May 16 12:18:39 EDT 2008


This is a simple bug report, more or less. The type of
Data.IntMap.intersectionWith is too restrictive. Presently (GHC 8.2, it's declared as
(a->b->a) -> IntMap a -> IntMap b -> IntMap a, but if you just remove
the type declarations it's inferred as (a->b->c) -> IntMap a -> IntMap
b -> IntMap c. Similarly for intersectionWithKey. The more general
a->b->c type is also the type of Data.Map.intersectionWith, and it's
quite useful, such as (intersectionWith (,))


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