🚀 go-pugleaf

In article <24955@louie.udel.EDU>, new@udel writes:
>One thing I have always liked about the C language was the separation
>between the "header" files (.h) and the "code" files (.c).

>Does anyone know of any relatively popular languages that allow this
>sort of separation other than C and C++?  If not, why not?
Discussion?

ML can do the same sort of thing:

	signature SMALL_PART =
	  sig
	    type ... and ... and ...
	    val ... : ty1 and ... : ty2 and ...
	  end;

	signature ANOTHER_SMALL_PART = ...

	signature ENTIRE_THING =
	  sig
	    include SMALL_PART
	    include ANOTHER_SMALL_PART
	  end

This gives you inclusion of interfaces. There's also nesting of
interfaces; the ENTIRE_THING signature could specify two sub-modules
with smaller signatures. The actual module to match ENTIRE_THING could
be a single object containing all the type specs and functions, or
could be built from two (or more) separate ones:

	functor EntireThing(structure Part1: SMALL_PART
			    structure Part2: ANOTHER_SMALL_PART
			   ) =
	  struct
	    open Part1		(* simple case: inclusion. *)
	    open Part2
	  end;

You can also have several implementations maching the same interface
of course (but you said you weren't interested in that).

>				 -- Darren

		Nick.
--
Nick Rothwell,	Laboratory for Foundations of Computer Science, Edinburgh.
		nick@lfcs.ed.ac.uk    <Atlantic Ocean>!mcvax!ukc!lfcs!nick
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               Fais que ton reve soit plus long que la nuit.