from*DescList* missing from IntMap and IntSet

[hseg]

fromDescList, fromDescListWith, fromDescListWithKey, fromDistinctDescList are all missing from IntMap.

[treeowl]

Good point. Do you want to try writing them?

[hseg]

A cursory glance reveals some structural differences between Map.fromAscList and IntMap.fromAscList, with the former basically doing fromList . groupWith f and marking everything in sight as INLINABLE to get the relevant fusion, whereas the latter has a fromMonoListWithKey which seems to be a fused version of the above with a flag controlling whether the user asserts the input is distinct, and for some reason is marked everywhere as NOINLINE.
Probably the sane thing to do is clone the IntMap code, but the inconsistency is jarring enough to make me second-guess myself. That, and fromMonoListWithKey is complex enough to make me doubt I can easily flip it.
Willing to try with more guidance, but this looks a bit too heavy for me right now.

[treeowl]

Map needs inlining to specialize to an Ord instance. IntMap gets much less, if any, benefit from large-scale inlining, so code size is prioritized. I think a lot of the other differences are about differences in the data structure shapes. Anyway, I can give it a shot.

[meooow25]

PRs welcome, if anyone wants to try.

The implementation of fromAscList* is simpler now after #1123, and can be a template for fromDescList*.