On Monday, November 7, 2016 at 11:19:22 AM UTC-8, David K. Storrs wrote:
> Out of curiosity, why do you want this?
Some context: https://github.com/jackfirth/lens/issues/290
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Out of curiosity, why do you want this?
On Mon, Nov 7, 2016 at 1:27 PM, Alex Knauth wrote:
>
> > On Nov 4, 2016, at 4:58 PM, Sam Tobin-Hochstadt
> wrote:
> >
> > Here's an example:
>
> Oh, so this only raises an error when creating an *instance* of y, not
> when creating the struct-type for y.
> On Nov 4, 2016, at 4:58 PM, Sam Tobin-Hochstadt wrote:
>
> Here's an example:
Oh, so this only raises an error when creating an *instance* of y, not when
creating the struct-type for y. Is there any way to make it raise an error on
the make-struct-type call?
Alex Knauth
> #lang racket
>
Here's an example:
#lang racket
(define (make-final-struct-type name count)
(define-values (type constructor predicate accessor mutator)
(make-struct-type name #f count 0))
(values (chaperone-struct-type type (λ _ (error 'fail1))
(λ _ (error 'fail2))
Look at `chaperone-struct-type`:
http://docs.racket-lang.org/reference/chaperones.html?q=chaperone-struct-type#%28def._%28%28quote._~23~25kernel%29._chaperone-struct-type%29%29
You can just have the guard always error.
Sam
On Fri, Nov 4, 2016 at 4:49 PM, Alex Knauth wrote:
>
>> On Nov 4, 2016,
> On Nov 4, 2016, at 4:43 PM, Sam Tobin-Hochstadt wrote:
>
> Typed Racket chaperones the struct type to prevent further extension.
Ok, thanks. Where would I go to see how I would create a chaperone like this?
> Sam
>
> On Fri, Nov 4, 2016 at 4:29 PM, Alex Knauth wrote:
>> Hello,
>>
>> Is th
Typed Racket chaperones the struct type to prevent further extension.
Sam
On Fri, Nov 4, 2016 at 4:29 PM, Alex Knauth wrote:
> Hello,
>
> Is there a way to enforce that a particular struct is final, in other words,
> that no one can declare a sub-struct of it?
>
> (struct foo (a b c) #:final)
>
Hello,
Is there a way to enforce that a particular struct is final, in other words,
that no one can declare a sub-struct of it?
(struct foo (a b c) #:final)
(struct bar foo (d e f))
; should produce a syntax error similar to:
; struct: cannot inherit from the final struct foo
(make-struct-type
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