http://users.skynet.be/jyp/DData/doc/index.html
I only looked at Set and Map
Any comment is welcome. (Including "I support this proposal" :))
Yes, I support this proposal.
Maybe the documentation to the "0rdered lists" section can be improved.
Set.toAscList is not really necessary as it is the same as Set.toList. In order to be a proper function, the result of Set.tolist must return a sorted list without duplicates, since equal sets should yield equal lists, if converted by Set.toList. (For debugging purposes this may be violated, though.) Returning a descending list is not necessary, because this can simply be achieved by reversing, if needed.
The functions Set.fromAscList and Set.fromAscDistinctList should be marked as "unsafe", since it's not clear what sets result if the input is not ascending (and/or has duplicates). Furthermore, already for Set.fromList I expect it to be linear, if the input list happens to be
ascending.
"Set.map" is (still) missing. There are two variants of map functions with type:
(Ord a, Ord b) => (a -> b) -> Set a -> Set b
The first variant requires the function argument f to be strongly ascending, a < b => f a < f b, and corresponds to a map on the associated ascending lists.
The second variant does not restrict the function argument but may result in a set of smaller size. Maybe this variant should be called "Set.image".
The first variant, maybe call it "Set.mapAsc", is again "unsafe", since the argument function may not be ascending. (The descending case can be ignored.)
The same argument about "ordered lists" apply to the Map module. In addition, it would be nice if there were a variant of "Map.keys" that returns a set of keys, since the invariant that the keys are ascending and distinct may easily get lost, if not captured by the Set type. A straight forward implementation is:
Map.keySet = Set.fromDistinctAscList . Map.keys
The use of "Set.fromDistinctAscList" is safe in this case, but - alas - Map needs to import Set. (But maybe there is even a faster implementation of Map.keySet that exploits the internal representation.)
Christian
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