package ppx_deriving

Sets over ordered types.

This module implements the set data structure, given a total ordering function over the set elements. All operations over sets are purely applicative (no side-effects). The implementation uses balanced binary trees, and is therefore reasonably efficient: insertion and membership take time logarithmic in the size of the set, for instance.

The Make functor constructs implementations for any type, given a compare function. For instance:

module IntPairs =
  struct
    type t = int * int
    let compare (x0,y0) (x1,y1) =
      match Stdlib.compare x0 x1 with
          0 -> Stdlib.compare y0 y1
        | c -> c
  end

module PairsSet = Set.Make(IntPairs)

let m = PairsSet.(empty |> add (2,3) |> add (5,7) |> add (11,13))

This creates a new module PairsSet, with a new type PairsSet.t of sets of int * int.