Re: [Caml-list] Style and organization of code

[skaller <skaller@users.sourceforge.net>]

On Wed, 2007-03-14 at 17:25 -0500, ian wrote:
> I'm looking for a guidebook or just some rules of thumb on how to organize my
> OCaml code.

> But that would make the definition of solveHardProblem really long -- several
> screens of text -- which I've been taught to avoid.  

Yeah, this is a problem with functional programming .. i have
functions that are hundreds of lines long.

Generally you want to factor out functions with minimal coupling
to the enclosing function's environment, and leave them in
if they're heavily coupled.

Furthermore if that helper is reasonably general OR it has
some semantics which are separately understandable .. you can
put that function in a separate file for additional decoupling.

> Is it wrong to use a module
> to hide those functions if the module signature will contain only that of
> solveHardProblem?

That's the normal thing to do.

Furthermore if that helper is reasonably general OR it has
some semantics which are separately understandable .. you can
put that function in a separate file for additional decoupling.

This has the downside that Ocaml's namespace management is weak,
so your function is now fully public.

But smaller modules are more pleasing and easier to manage,
so it is probably worth while.

In particular if you use 'open Module' a lot, then the
dependencies both ON and OF that module are more refined
and explicit. This is also a reasonable first order approximation
to measuring the 'coupling' between components.

> And say you DO choose to use a module...  The OCaml documentation says that the
> compiler can automatically infer the signature without the need to create a .mli
> file for it.  Does anyone actually use that feature in practice, or is creating
> a sig hard-wired to the act of creating a struct?

I personally never do this: there is always an mli file for 
every ml file -- even if the build script makes it by copying
the mli file.

-- 
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net