On 4/10/07, Hugo Ferreira <[EMAIL PROTECTED]> wrote:
> Hello,
>
> Nicolas Pouillard wrote:
> > On 4/8/07, Martin Jambon <[EMAIL PROTECTED]> wrote:
> >> On Sat, 7 Apr 2007, Nicolas Pouillard wrote:
> >>
> >>> On 4/5/07, Martin Jambon <[EMAIL PROTECTED]> wrote:
> >>>> On Thu, 5 Apr 2007, Hugo Ferreira wrote:
> >>>>
> >
[...]
>
> Just a comment: my greatest difficulty with camlp4 is twofold:
>
> - knowing how the AST maps to the actual Ocaml syntax.
You can ask to camlp4 itself!
Using the old one...
$ cat test.ml
(* here is some expression that you want to understand *)
fun e -> <:expr< let x= HEAP in $e$ >>
$ camlp4o q_MLast.cmo pr_o.cmo test.ml
let _ =
fun e ->
MLast.ExLet
(_loc, false, [MLast.PaLid (_loc, "x"), MLast.ExUid (_loc, "HEAP")], e)
> - knowing when/where the camlp4 parser does its transformations so that
> I may alter these transformations (match and replace expressions).
That's not really transformations of the AST.
However there is some grammar tranformations:
When you add a rule to a grammar entry at a specific level camlp4
insert it in a tree to factor out the prefix or rules as much as
possible.
e1 = SELF; "+"; e2 = SELF -> ...
e1 = SELF; "*"; e2 = SELF -> ...
is in fact something like:
e1 = SELF; [ "+"; e2 = SELF -> ... | "*"; e2 = SELF -> ... ]
So if you add something make it as much as possible a prefix of existing ones.
[...]
> In effect I write Ocaml "expression" which is automatically matched and
> I only need write an Ocaml expression to introduce the changes I want.
> All this using simply using the quotation system. The rules and the AST
> structure itself should, in my humble opinion, be avoided.
Indeed, extension that are highly dependent on the actual grammar
should be avoided.
> This will also allow the underlying camlp4 system to change without unduly
> affecting user's code.
Exactly!
--
Nicolas Pouillard
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