[racket-dev] Regular expression types [was Re: [racket-bug] all/14455: wrong type for hash]

From: Neil Toronto (neil.toronto at gmail.com)
Date: Sat Apr 19 19:24:42 EDT 2014

Are there type systems that can? It seems like you could specify this 
type and similar ones using regular expressions.

In my research, I'll probably use regular expressions to represent sets 
of strings. I've been curious about how well regular-expression-like 
things generalize to cartesian products with repeating structure.

Neil ⊥

On 04/19/2014 03:44 PM, Eric Dobson wrote:
> The type for hash is conservative. TR currently cannot express the
> alternating requirement that hash requires.
> On Sat, Apr 19, 2014 at 2:40 PM,  <alexander at knauth.org> wrote:
>> A new problem report is waiting at
>>    http://bugs.racket-lang.org/query/?cmd=view&pr=14455
>> Reported by Alex Knauth for release: 6.0
>> *** Description:
>> the type for hash appears to be (All (a b) (-> (HashTable a b))), so it's not letting me supply it with arguments, saying that it expects 0 arguments
>> *** How to repeat:
>> #lang typed/racket
>> (hash 0 0)

Posted on the dev mailing list.