[plt-scheme] mutation in typed scheme structs

Ah, I didn't think of that, it works fine - thanks a lot for the quick answer!

Ciao,
Sigrid




Am 13.04.2010 um 17:13 schrieb David Van Horn:

> On 4/13/10 11:10 AM, keydana at gmx.de wrote:
>> Hi,
>> 
>> one question regarding typed scheme: can I use mutation in typed scheme structs, like e.g.
>> 
>> (define-struct: pt ([x : Real] [y : Real]))
>> (define p (make-pt 1 2))
>> (set-pt-x! p 22)
>> 
>> I tried adding #:mutable to one of the fields with different syntaxes, but didn't get it to work - could someone give me a little hint please?
> 
> I believe you can only specify structure-level (not field-level) mutability in Typed Scheme:
> 
> #lang typed/scheme
> (define-struct: pt ([x : Real] [y : Real]) #:mutable)
> (define p (make-pt 1 2))
> (set-pt-x! p 22)
> 
> David