Inline vs. Inlinable?

[isturdy]

member is marked INLINABLE while notMember is marked INLINE, despite both habing essentially identical structure. Other things that are INLINE while similar functions are INLINABLE: foldlWithKeyWith, foldrWithKeyWith (in these cases I would expect the API wrapper functions to be INLINE and the longer core function INLINABLE, if anything), updateExtremity.

Functions missing any such pragma that I think may want one: null, empty, elems, assocs, keys, unionWith, unionWithKey, unions, unionsWith, intersectionWithKey, map, mapKeys, toAscList, toDescList, filter.

Is there some reason to these decisions that I have overlooked?