The Mixture project provides a comprehensive mixins library for the OCaml module system.

The Mixture_Compare module defines a mixin which derives all classical comparison operators (in prefix and infox form) from a compare function. For instance

module PlayingCard =
struct
  type card =
  | Card of regular
  | Joker
  and regular = { suit : card_suit; name : card_name; }
  and card_suit = Heart | Club | Spade | Diamond
  and card_name =  Ace | King | Queen | Jack | Simple of int

  module Basis =
  struct
    type t = card
    let compare = Pervasives.compare
  end

  module CompareMethods =
    Mixture_Compare.Make(Basis)

  include Basis
  include CompareMethods
end

The module PlayingCard has prefix and infix comparison operators derived from compare so, if a and b are cards, one can write PlayingCard.lt a b or equivalently PlayingCard.Infix.(a < b).

The growing list of mixins defined in the library is:

• Mixture_Applicative
• Mixture_Compare
• Mixture_Format
• Mixture_Parse
• Mixture_Monad
• Mixture_FoldRight
• Mixture_FoldAssoc

It is written by Michael Grünewald and is distributed as a free software: copying it and redistributing it is very much welcome under conditions of the CeCILL-B licence agreement, found in the COPYING and COPYING-FR files of the distribution.

It is easy to install Mixture using opam and its pinning feature. In a shell visiting the repository, say

% autoconf
% opam pin add mixture .

It is also possible to install Mixture manually. The installation procedure is based on the portable build system BSD Owl Scripts written for BSD Make.

1. Verify that prerequisites are installed:

   • BSD Make
   • BSD OWl
   • OCaml
   • Broken
   • GNU Autoconf

2. Get the source, either by cloning the repository or by exploding a distribution tarball.

3. Optionally run autoconf to produce a configuration script. This is only required if the script is not already present.

4. Run ./configure, you can choose the installation prefix with --prefix.

5. Run make build.

6. Optionally run make test to test your build.

7. Finally run make install.

Depending on how BSD Make is called on your system, you may need to replace make by bsdmake or bmake in steps 5, 6, and 7. The GNU Make program usually give up the ghost, croaking *** missing separator. Stop. when you mistakingly use it instead of BSD Make.

Step 7 requires that you can su - if you are not already root.

Michael Grünewald in Bonn, on August 11, 2015