(old) camlp4 question

(old) camlp4 question

[Pietro Abate]

Hi all,
I want to write a type like this in camlp4 :
type ('a,'b) b = [ `T of 'b ]
type a = ('b,int) b as 'b

Suppose I have a list of ctyp [<:ctyp< 'b >>;<:ctyp< int >>; ... ]
How can I write the type ('b,int) b as 'b ??

I've tried with <:ctyp< type a = b ($list:l$) as 'b >> but the result
is incorrect ... what is the right syntax ?

pietro

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Re: [Caml-list] (old) camlp4 question

[Nicolas Pouillard]

On 4/11/07, Pietro Abate <Pietro.Abate@anu.edu.au> wrote:
> Hi all,
> I want to write a type like this in camlp4 :
> type ('a,'b) b = [ `T of 'b ]
> type a = ('b,int) b as 'b
>
> Suppose I have a list of ctyp [<:ctyp< 'b >>;<:ctyp< int >>; ... ]
> How can I write the type ('b,int) b as 'b ??
>
> I've tried with <:ctyp< type a = b ($list:l$) as 'b >> but the result
> is incorrect ... what is the right syntax ?
>

Two things:

The `as' must be surrounded by parentheses  (('b,int) b as 'b).

And a type declaration is not a type, you can use a str_item or a sig_item.

Here we go: <:str_item< type a = (b ($list:l$) as 'b) >>;;

-- 
Nicolas Pouillard

Re: [Caml-list] (old) camlp4 question

[Pietro Abate]

On Wed, Apr 11, 2007 at 01:43:48PM +0200, Nicolas Pouillard wrote:
> Two things:
> The `as' must be surrounded by parentheses  (('b,int) b as 'b).
> And a type declaration is not a type, you can use a str_item or a sig_item.
> Here we go: <:str_item< type a = (b ($list:l$) as 'b) >>;;

Doesn't quite work for me... This is my usage pattern.

I've a toplevel <:str_item< type $list:l$ >> where l is a list of 
((_loc * string),(string * (bool * bool)) list, ctyp ,?? list)
and ?? list is a list of something that I haven't figure out yet (the
manual says <:str_item< type $list:sslt$ >>: type declaration).

to write type a = (b ($list:l$) as 'b) , I've to give a list l
of one element as
((_loc,"a"),[], <:ctyp< (b ($list:[<:ctyp< 'b >>,<:ctyp< int >>]$) as 'b) >>, [])

My problem is to write the type (('b,int) b as 'b) as a ctyp .

I want to write it in this way as both l and the list of type variables
in (('b,int) b as 'b) are not fixed. Moreover types in <:str_item<
type $list:l$ >> can be mutually recursive.

thanks :)
p

-- 
++ Blog: http://blog.rsise.anu.edu.au/?q=pietro
++ 
++ "All great truths begin as blasphemies." -George Bernard Shaw
++ Please avoid sending me Word or PowerPoint attachments.
   See http://www.fsf.org/philosophy/no-word-attachments.html

Re: [Caml-list] (old) camlp4 question

[Nicolas Pouillard]

On 4/12/07, Pietro Abate <Pietro.Abate@anu.edu.au> wrote:
> On Wed, Apr 11, 2007 at 01:43:48PM +0200, Nicolas Pouillard wrote:
> > Two things:
> > The `as' must be surrounded by parentheses  (('b,int) b as 'b).
> > And a type declaration is not a type, you can use a str_item or a sig_item.
> > Here we go: <:str_item< type a = (b ($list:l$) as 'b) >>;;
>
> Doesn't quite work for me... This is my usage pattern.
>
> I've a toplevel <:str_item< type $list:l$ >> where l is a list of
> ((_loc * string),(string * (bool * bool)) list, ctyp ,?? list)
> and ?? list is a list of something that I haven't figure out yet (the
> manual says <:str_item< type $list:sslt$ >>: type declaration).

?? is for constraints on type parameters (you can leave it empty)

> to write type a = (b ($list:l$) as 'b) , I've to give a list l
> of one element as
> ((_loc,"a"),[], <:ctyp< (b ($list:[<:ctyp< 'b >>,<:ctyp< int >>]$) as 'b) >>, [])
>
> My problem is to write the type (('b,int) b as 'b) as a ctyp .

Hum I see it's the type application that is like any other application
in revised.

int list -> list int

(string, int) table -> table string int

<:ctyp< (b 'b int as 'b) >>

Regards,

-- 
Nicolas Pouillard