On Thu, Mar 17, 2016 at 4:17 PM, Matthew Butterick <m...@mbtype.com> wrote:
>
> On Mar 17, 2016, at 2:05 PM, Andrew Gwozdziewycz <apg...@gmail.com> wrote:
>
> I am imagining an API that utilizes SCSH style regexes but allows you to
> do something like this (fictional):
>
> (define-values (area prefix line) (sre-match (: (= digits 3) (_? "-") (=
> digits 3) (_? "-") (= digits 3))))
>
>
>
> Racket's `match` is not far from this. In fact maybe I shouldn't be
> thinking in terms of hacking regexps, but rather making a new match
> expander. For instance, you can destructure a list like so:
>
> (match '("foo" "-42.3" "bar")
> [(list a (? string->number b) c) 'yay]
> [else 'boo])
>
> So it would extend logically to this pseudocode:
>
> (match "foo-42.3bar"
> [(string-append a (? string->number b) c) 'yay]
> [else 'boo])
>
Yup! Exactly. I really had `match` in mind. I'm not sure why you wouldn't
use regexes underneath though. As you have it, you'd be forced to call
`string->number` on every subsequence, where as constructing a regex with
grouping seemingly does this in effectively 1 pass (with possible back
tracking of course).
Still, the idea is extremely solid, and I would use such a thing
constantly.
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