Re: Ocaml scripting

sheath@mail.com (Simon H.) writes:

> Okay. I'm building a text-adventure engine in Ocaml, and basically, I
> want certain features to be scriptable. Like, the game-writer can
> write a function to trigger an event when certain criteria are met.
> This, of course, means that it has to be able to load and /evaluate/
> text files, returning an Ocaml function. Of course I could write my
> own interpreter and mini-scripting language, but that seems a little
> like overkill since it's gonna have a total of maybe two dozen
> functions.
>
> Now, a wholly interpreted language like Lisp or Python comes with an
> "eval" function, which would do exactly what I want, but OCaml is
> compiled and doesn't have an equivilant, as far as I can find. The
> closest thing I can think of would be ocamlmktop, and using that would
> just make things rather more complicated than I would like to deal
> with, what with having to hack the new toplevel into acting like a
> game engine instead of a toplevel.
>
> So is there some nice easy way to do this, or shall I start writing an
> interpreter?

Well, true enough, you can already use the Dynlink library to
dynamically load ocaml bytecode into a running program. You could also
include the compiler in your application to do the compilation on the
fly: much more tricky, and not supported. Moreover, read the ocaml
license: including compiler sources puts you under the the QPL, which
is a very restrictive open-source license.

And, ocaml as a language is not at all conceived as a scripting
language: lots of errors at compile time, no handling of dynamic types,
etc...

So, do yourself a favor: it is so incredibly easy to write a small
interpreter in ocaml! Choose your tools: ocamlex/ocamlyacc or
Genlex/stream parsers (this last may be simpler). Then the interpreter
itself is simply trivial.

Still, I sometimes think that it would be nice to have a standard
scripting language for caml. Ideally, this would be just the core of a
language, and could be extended easily for customization.

---------------------------------------------------------------------------
Jacques Garrigue Kyoto University garrigue at kurims.kyoto-u.ac.jp
<A HREF=http://wwwfun.kurims.kyoto-u.ac.jp/~garrigue/>JG</A>