From: Jacques Carette <carette@mcmaster.ca>
To: skaller <skaller@users.sourceforge.net>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] how to implement generic operators
Date: Mon, 24 Oct 2005 15:27:51 -0400 [thread overview]
Message-ID: <435D35B7.2080905@mcmaster.ca> (raw)
In-Reply-To: <1130131250.28443.79.camel@rosella>
skaller wrote:
>I would clearly need some representation like:
>
> Assoc of op * term list
>
>and then some kind of fold which works for all different binary op,
>where now 'op' is defined by the user.
>
>So crudely the question is: what is the representation of 'op'
>required so the generic fold can create a wide class of
>generic n-ary operations from binary ones?
>
>
You really need your operations to be left-associative for that to make
sense... But in my toy interpreter for a subset of Maple (written in
Ocaml), I have
type op = term -> term -> term * term
and then in the eval() function for a term, a case
| Assoc ((f,init), l) -> List.fold_left f init l
f can be created from a term by applying a term-level lambda, so that
when you ask for
>Note the data for op will be obtained by parsing in the input
>program, so cannot consist of just a fixed list of variants.
>
>
that can be done too.
>I have a feeling MetaOcaml can do this already.
>
>
Yes and no. Yes, it can be done by staging a very finely crafted
evaluator. But doing that is very, very difficult given the current
state-of-the-art [typed PE for typed languages is hard]. Or merely
difficult if you write everything CPS style. But it is most definitely
not something you get right out of the box.
Jacques C.
next prev parent reply other threads:[~2005-10-24 19:27 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-24 5:20 skaller
2005-10-24 18:26 ` Ant: [Caml-list] " Martin Chabr
2005-10-25 1:09 ` skaller
2005-10-25 1:56 ` skaller
2005-10-24 19:27 ` Jacques Carette [this message]
2005-10-25 1:43 ` skaller
2005-10-25 15:52 ` Jacques Carette
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