Re: [Caml-list] Re: Syntax extensions without Camlp4

[Wojciech Meyer <wojciech.meyer@googlemail.com>]

Gerd Stolpmann <info@gerd-stolpmann.de> writes:

> Am Donnerstag, den 31.05.2012, 12:01 -0400 schrieb bob zhang:
> I guess you are missing Alain's point here. He suggests to use normal
> pattern matching directly on parsetrees, as in
>
> match expr with
>  | Pexp_ident id -> Pexp_ident (tranform id)
>  | Pexp_contant c -> Pexp_constant c
>  | ...
>
> instead of using camlp4 syntax quotations (no <<...>> stuff for syntax
> manipulation anymore).

I admit quotations are *way* better to construct the code, they are
syntax aware but also reassemble string manipulation at the same
time. If somebody has generated some more serious program using
quotations then she can't stand using normal way by constructing via the
data constructors. I can compare, because I have used both ways for the
same project. Of course normal ASTs have it's wide applications, what is
shown above is a transform, and not strictly a code generation - usually
I have intermediate AST on the left hand side pattern match and on the
right hand side quotations. So I can't say quotations are not useful,
they are quite much. If the quotations could be as lightweight as
brackets-escape notations of MetaOCaml it would be brilliant. (I'm
really talking about code generation - and not extending the syntax).

Please see [1].

I'd support the idea of having quotations for the parse trees.

-- 
Wojciech Meyer
http://danmey.org

[1] http://www.eecs.harvard.edu/~mainland/ghc-quasiquoting/mainland07quasiquoting.pdf