[racket] JSExprs and hashtables

Would there be a more general solution that wouldn’t be specific to just hash-tables?

On Jan 19, 2015, at 9:38 AM, Sam Tobin-Hochstadt <samth at cs.indiana.edu> wrote:

> This is a correct improvement to Typed Racket -- I'll make it shortly.
> 
> Sam
> 
> On Mon, Jan 19, 2015 at 8:41 AM, Alexander D. Knauth
> <alexander at knauth.org> wrote:
>> 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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