[Ur] Regular expressions DSEL?

[Adam Chlipala]

It's definitely not a crazy idea to connect to standard regexp 
functionality, say PCRE on the server and built-in JavaScript stuff on 
the client, via the FFI, with a richly typed interface.  Let me know if 
you have any specific questions on how to go about it.  Ziv's type 
signature examples should be helpful as a starting point.

On 02/20/2017 12:00 AM, Artyom Shalkhakov wrote:
> 2017-02-20 10:47 GMT+06:00 <fold at tuta.io <mailto:fold at tuta.io>>:
>
>     Maybe just define another attribute in basis.urs?
>
>     It would be much interesting to define a DSEL though. I have not
>     seen any attempts to create a DSEL for regular expressions.
>
>
> Indeed! And it seems like it would be a nice exercise as well having 
> some practical uses to it.
>
> I envision something along the lines of:
>
> datatype RegExp = ... (* constructors *)
>
> type t (* abstract, not exported outside the module *)
> val compile : RegExp -> t (* the trusted function *)
> val matches : string -> t -> bool (* check if passed-in string matches 
> the expression *)
>
> And the implementation might use something unsafe (like a string, or 
> an actual regexp object in JS). Then we could offload the 
> interpretation of regexps to an off-the-shelf library. The [compile] 
> function would print and escape the AST to a regexp string, and the 
> Ur/Web compiler might actually optimize all of this away.
>
> If we are to take care of matching subgroups, that would require a 
> more complicated type. I guess that should be doable as well, but I 
> don't see immediately how to handle this.
>
>
>
>     20. Feb 2017 16:28 by artyom.shalkhakov at gmail.com
>     <mailto:artyom.shalkhakov at gmail.com>:
>
>
>         Hello all,
>
>         'm doing form validation stuff, following examples on MDN. [1]
>
>         It seems like Ur/Web doesn't handle regular expressions?
>
>         I guess it should not be too diffcult to define a DSEL in
>         Ur/Web (just AST constructors and a few trusted functions:
>         e.g. [compile : AST -> regexp], where [regexp] is an abstract
>         type, or maybe just a string :-)) and have it work at least in
>         the browser.
>
>         Could somebody point me in the right direction here?
>
>         -- 
>         Cheers,
>         Artyom Shalkhakov
>
>         [1]
>         https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/Constraint_validation
>         <https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/HTML5/Constraint_validation>
>
>
>
>
> -- 
> Cheers,
> Artyom Shalkhakov
>
>
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