Data.Map.Extensions
drop
take
slice
slicei
keepKeys
dropKeys
filterM
transpose
scanl1
scanr1
groupBy
groupKeysBy
groupElemsBy
fromList2
fromLists
lookup2
lookup3
lookup4
type Lookup ix1 tgt
type Lookup2 ix1 ix2 tgt
type Lookup3 ix1 ix2 ix3 tgt
type Lookup4 ix1 ix2 ix3 ix4 tgt