[Caml-list] type synonym for polymorphic variant

[Caml-list] type synonym for polymorphic variant

[Ashish Agarwal]

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I've been doing this in some code for years:

type s = [`A | `B]
type t = [s]

but just discovered it works only because the code was passing through
camlp4. Without camlp4, it fails. You can try in utop with and without
doing #camlp4o.

Is there some way to get the above to work without camlp4? AFAICT, the
grammar allows it, so the normal parser is wrong here.

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Re: [Caml-list] type synonym for polymorphic variant

[Haoyang Wang]

> On Oct 1, 2015, at 2:41 PM, Ashish Agarwal <agarwal1975@gmail.com> wrote:
> 
> type s = [`A | `B]
> type t = [s]

type t = s

Re: [Caml-list] type synonym for polymorphic variant

[Ashish Agarwal]

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Embarrassing. I don't know why I thought I had to put brackets... Thanks!

On Thu, Oct 1, 2015 at 5:47 PM, Haoyang Wang <hywang@pobox.com> wrote:

> > On Oct 1, 2015, at 2:41 PM, Ashish Agarwal <agarwal1975@gmail.com>
> wrote:
> >
> > type s = [`A | `B]
> > type t = [s]
>
> type t = s
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>

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Re: [Caml-list] type synonym for polymorphic variant

[Daniel Bünzli]

Le jeudi, 1 octobre 2015 à 23:06, Ashish Agarwal a écrit :
> Embarrassing.

Not really, since you are allowed to write  

type t = [ s | `C ]

Daniel

Re: [Caml-list] type synonym for polymorphic variant

[Ashish Agarwal]

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On Thu, Oct 1, 2015 at 6:23 PM, Daniel Bünzli <daniel.buenzli@erratique.ch>
wrote:

> Le jeudi, 1 octobre 2015 à 23:06, Ashish Agarwal a écrit :
> > Embarrassing.
>
> Not really, since you are allowed to write
>
> type t = [ s | `C ]
>

Right, that's the whole reason my brain got stuck thinking the brackets
need to be there. This is some auto-generated code, and sometimes I do
extend the type, so the brackets were always being put in.

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Re: [Caml-list] type synonym for polymorphic variant

[Ashish Agarwal]

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On Thu, Oct 1, 2015 at 6:20 PM, Thomas Refis <thomas.refis@gmail.com> wrote:

> Note the you could also do "type t = [ | s ]"
>

Actually I had tried that, but it doesn't work.



>
> 2015-10-01 18:06 GMT-04:00 Ashish Agarwal <agarwal1975@gmail.com>:
> > Embarrassing. I don't know why I thought I had to put brackets... Thanks!
> >
> > On Thu, Oct 1, 2015 at 5:47 PM, Haoyang Wang <hywang@pobox.com> wrote:
> >>
> >> > On Oct 1, 2015, at 2:41 PM, Ashish Agarwal <agarwal1975@gmail.com>
> >> > wrote:
> >> >
> >> > type s = [`A | `B]
> >> > type t = [s]
> >>
> >> type t = s
> >>
> >> --
> >> Caml-list mailing list.  Subscription management and archives:
> >> https://sympa.inria.fr/sympa/arc/caml-list
> >> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> >> Bug reports: http://caml.inria.fr/bin/caml-bugs
> >
> >
>

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Re: [Caml-list] type synonym for polymorphic variant

[Daniel Bünzli]

Le jeudi, 1 octobre 2015 à 23:28, Ashish Agarwal a écrit :
> On Thu, Oct 1, 2015 at 6:20 PM, Thomas Refis <thomas.refis@gmail.com (mailto:thomas.refis@gmail.com)> wrote:
> > Note the you could also do "type t = [ | s ]"
>  
> Actually I had tried that, but it doesn't work.

It does here (4.02.3).  

Daniel

Re: [Caml-list] type synonym for polymorphic variant

[Ashish Agarwal]

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Oh I see it is whitespace sensitive:

"type t = [|s]" fails
"type t = [ |s]" works


On Thu, Oct 1, 2015 at 6:35 PM, Daniel Bünzli <daniel.buenzli@erratique.ch>
wrote:

> Le jeudi, 1 octobre 2015 à 23:28, Ashish Agarwal a écrit :
> > On Thu, Oct 1, 2015 at 6:20 PM, Thomas Refis <thomas.refis@gmail.com
> (mailto:thomas.refis@gmail.com)> wrote:
> > > Note the you could also do "type t = [ | s ]"
> >
> > Actually I had tried that, but it doesn't work.
>
> It does here (4.02.3).
>
> Daniel
>
>
>

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