[racket] JSExprs and hashtables

I managed to fix this for your example by inserting these 3 lines into typed-racket/types/remove-intersect.rkt after line 67:
         [(list-no-order (Value: (not (? hash?)))
                         (or (? Hashtable?) (? HashtableTop?)))
          #f]
There is probably a better solution though.

On Jan 19, 2015, at 7:36 AM, Alexander D. Knauth <alexander at knauth.org> wrote:

> Since hash-tables can be mutable as far as TR knows, (HashTable Symbol String) is not a subtype of (HashTable Symbol JSExpr).
> To work around this, you can do this:
> #lang typed/racket/base
> (require typed/json)
> (: jsx JSExpr)       ; <-- jsx is what I ultimately want.
> (define jsx (ann #hasheq((a . "val1") (b . "val2") (c . "val3")) (HashTable Symbol JSExpr)))
> 
> Or this would work too:
> #lang typed/racket/base
> (require typed/json)
> (: jsx (HashTable Symbol JSExpr))       ; <-- jsx is what I ultimately want.
> (define jsx #hasheq((a . "val1") (b . "val2") (c . "val3")))
> 
> Or you could use (inst make-immutable-hasheq Symbol JSExpr) instead of using #hasheq, and it would do the same thing.
> 
> 
> On Jan 19, 2015, at 1:28 AM, Jordan Johnson <jmj at fellowhuman.com> wrote:
> 
>> Hi all,
>> 
>> I’ve been trying to create JSExprs, as defined in the typed/json library. This is one of those instances where it seems like I must be making things harder than they should be, but I’m still feeling like a duck on rollerskates in TR, so I want to make sure I’m not missing an easier way to do it.
>> 
>> Would you please confirm if this is indeed a smallest-possible solution?
>> 
>> ;;;; begin
>> #lang typed/racket/base
>> 
>> (require typed/json)
>> 
>> (: jsx JSExpr)       ; <-- jsx is what I ultimately want.
>> 
>> ;; Attempt #1:
>> #;
>> (define jsx #hasheq((a . "val1") (b . "val2") (c . "val3")))
>> 
>> #| Resulting error:
>> Type Checker: type mismatch
>>   expected: JSExpr
>>   given: (HashTable Symbol String)
>> 
>> [This seems weird, since it seems like (HashTable Symbol String) should be
>>  a subtype of JSExpr. Is the problem that the typechecker can’t recognize
>>  the Strings as JSExprs?]
>> |#
>> 
>> ;; Attempt #N (shortest successful version I’ve found):
>> (define jsx
>>   (for/hasheq : (HashTable Symbol JSExpr) ([k '(a b c)]
>>                                            [v '("val1" "val2" "val3")])
>>     (values k v)))
>> ;;;; end
>> 
>> Regards,
>> Jordan
>> 
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