Comment author: jroewen

I don't know how to do a diff, so here's my breakdown of implementing this option again ocaml 3.08.4:

driver/compile.ml:
44:
+/- let initial = try
50:

• in
• List.fold_left (fun a b -> try Env.open_pers_signature b a with Not_found -> fatal_error (Printf.sprintf "cannot open cmi for %s" b)) initial !Clflags.open_libs

driver/main.ml:
98:

• let _open s = open_libs := s :: !open_libs

driver/main_args.ml:
29:

•  val _open : string -> unit
  

84:

• "-open", Arg.String F._open,

•       "<module>  Add <module> to the list of automatically opened modules";
  

driver/main_args.mli:
29:

•  val _open : string -> unit
  

tools/ocamlcp.ml:
57:

• let _open s = option_with_arg "-open" s

utils/clflags.ml:
21:
+and open_libs = ref ([] : string list) (* -open *)

As you can see, it's a fairly simple addition, though I suppose it could be abused as an alternative to using open, and would at the very least break ocamldep from finding correct dependencies.

Comment author: Yoric

This feature would be quite nice for Batteries Included, too, although for different reasons: where DST wishes to replace Pervasives with something smaller, we'd like to replace it with something bigger, without altering ocamlc.

At the moment, the only manner I can think of auto-opening a module is to pre-process every single source file and add "open Foo" at the first line. It's a bit wasteful.

Comment author: @mshinwell

The "-open" compiler flag now exists, which presumably solves this problem.