Inline vs. Inlinable?

`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?