Re: [Caml-list] beginner question about pattern matching

["vrotaru.md@gmail.com" <vrotaru.md@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1520 bytes --]

Rtag ((_,_,_,_) as t4) -> t4

Will this work? Writing from the phone

On Thu, Oct 19, 2017, 17:24 Matej Košík <mail@matej-kosik.net> wrote:

> On 10/19/2017 04:16 PM, vrotaru.md@gmail.com wrote:
> > [ Rtag (_,_,_,_) as rtag] -> rtag
>
> That is certainly possible.
> It is equivalent to:
>
>   | [rtag] -> rtag
>
> but that's not what I am trying to do.  :-/
>
> Instead of the whole
>
>   Rtag (something1, something2, something3, something4)
>
> I would like to bind just the 4-tuple
> (without the Rtag label).
>
> >
> >
> > On Thu, Oct 19, 2017, 16:39 Matej Košík <mail@matej-kosik.net <mailto:
> mail@matej-kosik.net>> wrote:
> >
> >     Hi,
> >
> >     I am trying to do simple pattern matching of these values:
> >     https://github.com/ocaml/ocaml/blob/trunk/parsing/parsetree.mli#L145
> >
> >     What I would like to do is:
> >
> >        | [Rtag the_whole_4_tuple] ->
> >            the_whole_4_tuple
> >
> >     However, when I try to do that, I am getting:
> >
> >       Error: The constructor Rtag expects 4 argument(s),
> >              but is applied here to 1 argument(s)
> >
> >     This:
> >
> >         | [Rtag (f1,f2,f3,f4)] ->
> >             f1,f2,f3,f4
> >
> >     of course works but (regardless of the chosen bound variable names),
> it looks amateurish.
> >
> >     What's the right way to do this?
> >     (I would like just to bind a 4-tuple and then return it)
> >
> >     (Apologies in advance for a stupid question.)
> >
>
>

[-- Attachment #2: Type: text/html, Size: 2357 bytes --]