tuareg-mode binary package in Ubuntu Bionic i386

 It handles automatic indentation of Objective Caml and Caml-Light
 code. Key parts of the code are highlighted using Font-Lock. It
 provides support to run an interactive OCaml toplevel and debugger.
 It works both with FSF Emacs and XEmacs.
 .
 This mode attempts to give better results than the one provided in
 the standard distribution of OCaml and which is available through the
 ocaml-mode package. Indentation rules are slightly different but
 closer to classical functional languages indentation. Tuareg-mode
 gives access to some functionalities from ocaml-mode when that
 package is installed.

Source package