[Ur] Regular expressions DSEL?

[Artyom Shalkhakov]

2017-02-20 10:47 GMT+06:00 <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:
>
>
> 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
>
>


-- 
Cheers,
Artyom Shalkhakov
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