[racket] occurrence typing for case?

I tried this:
(define-syntax-rule
  (case/type x-expr
    [t body ...] ...)
  (let ([x x-expr])
    (cond [((ann (make-predicate t) (Any -> Boolean : #:+ (t @ x-expr) #:- (! t @ x-expr)))
            x)
           body ...]
          ...))
  )
But it gave me these errors:
. Type Checker: type mismatch
  expected: (-> Any Boolean)
  given: (-> Any Boolean : String) in: (make-predicate t)
. Type Checker: type mismatch
  expected: (-> Any Boolean)
  given: (-> Any Boolean : (Listof Any)) in: (make-predicate t)
Even though I put the filters in, and if it’s ignoring my filters, then shouldn’t (-> Any Boolean : Type) be a subtype of (-> Any Boolean)?  

On May 11, 2014, at 8:54 PM, Alexander D. Knauth <alexander at knauth.org> wrote:

> 
> On May 11, 2014, at 7:41 PM, Eric Dobson <eric.n.dobson at gmail.com> wrote:
> 
>> The issue is that there is a temporary variable that has the same
>> value as x and TR cannot see that they point to the same location.
>> Your implementation of case/type has the same problem. I thought there
>> was a bug filed for it but couldn't find it so just filed one.
>> http://bugs.racket-lang.org/query/?cmd=view&pr=14502
> 
>> Use this:
>> #lang typed/racket
>> (require typed/rackunit)
>> 
>> (define-syntax-rule
>>  (case/type y x-expr
>>    [t1 body ...] ...)
>>  (let ([y x-expr])
>>    (cond [((make-predicate t1) y) body ...] ...))
>>  )
> This worked:
> #lang typed/racket
> (require typed/rackunit)
> (require syntax/parse/define)
> 
> (define-simple-macro
>   (case/type x:id
>     [t:expr body:expr ...+] ...)
>   (cond [((make-predicate t) x) body ...] ...)
>   )
> 
> (define (my-length x)
>   (case/type x
>     [String (string-length x)]
>     [(Listof Any) ((inst length Any) x)]
>     ;[VectorTop (vector-length x)]
>     ))
> (check-equal? (my-length "12345") 5)
> (check-equal? (my-length '(1 2 3 4 5)) 5)
> ;(check-equal? (my-length #(1 2 3 4 5)) 5)
> 
> Would something like that work for the typed version of case?  
> 
> ____________________
>  Racket Users list:
>  http://lists.racket-lang.org/users

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