Set.map

[vicuna]

Original bug ID: 6279
Reporter: @dbuenzli
Assigned to: @gasche
Status: resolved (set by @alainfrisch on 2016-12-06T18:37:19Z)
Resolution: fixed
Priority: normal
Severity: feature
Version: 4.01.0
Target version: 4.03.1+dev
Fixed in version: 4.04.0
Category: standard library

Bug description

would be nice. I have already written the following a few times in my life:

module Sset = Set.Make(String)
let sset_map f s = Sset.fold (fun e acc -> Sset.add (f e) acc) s Sset.empty

Thanks.

[vicuna]

Comment author: braibant

Also, in the same vein, I find myself writing a "of_list" function quite often

module MSet = struct
module Make(E:Set.OrderedType) =
struct
include Set.Make(E)
let of_list l = List.fold_right (add) l empty
end
end

I agree that this is a one-liner, but a frequent one...

[vicuna]

Comment author: @alainfrisch

@braibant: Set.of_list has already been added to trunk (will be available in OCaml 4.02), with a somewhat optimized implementation. See #4986.

[vicuna]

Comment author: @damiendoligez

May I remind everyone that the best place for such functions is "extended" libraries like Batteries and Jane Street Core?

[vicuna]

Comment author: @gasche

I'm postponing this to 4.04, but I proposed a pull request at:

#553