On Tuesday 03 April 2007 08:00, Andrej Bauer wrote:
> Brian Hurt wrote:
> > Does anyone  actually use this construct, and if so, for what?
>
> When I teach my students "theory" of programming languages, we write
> interpreters for mini languages. The recursive data structures are used
> to create closures of recursive functions, environments that contain
> mutually recursive values, closures of objects, etc. Life would be very
> hard without this feature.

There is a nice example here:

  http://www.ffconsultancy.com/ocaml/benefits/interpreter.html

Specifically, in the "eval" function:

    | ELetRec(var, arg, body, rest) ->
        let rec vars = (var, VClosure(arg, vars, body)) :: vars in
        eval vars rest

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
OCaml for Scientists
http://www.ffconsultancy.com/products/ocaml_for_scientists