[racket-dev] Removing Xexpr preference from Web Server

All dynamic/c does is apply three contracts in a particular order where one
is dynamic.

coerce/c strongly implies that the function is coercion, but its
implementation is similar to how the contract system must already use
projection functions (ie it cannot confirm that are actually projections; it
just applies them and uses the result)

The default value of current-response/c is a projection (any/c)

The compatibility library does not provide anything with the /c suffix that
is a coercion --- it gives normalize-response and automatically sets
current-response/c, but doesn't give anything that implies it is a
"contract"

Thus, the only thing that IMHO should irk you is xexpr-response/c that has
the /c suffix and uses coerce/c with an actual coercion. Is that the case?
What do you want me to call it?

Jay

On Sun, Dec 5, 2010 at 6:46 AM, Robby Findler
<robby at eecs.northwestern.edu>wrote:

> You've made a contract that isn't a projection, but does a coercion?
>
> I'd be happier if you instead made your own separate wrappers and
> didn't use "/c" and didn't call this a contract.
>
> Robby
>
> On Sun, Dec 5, 2010 at 12:29 AM, Jay McCarthy <jay.mccarthy at gmail.com>
> wrote:
> > Giving special consideration to Eli and YC's perspectives, I've come up
> with
> > the following way out of this problem.
> > I found a way to provide a global hook that is tasteful to me. I've
> created
> > "dynamic/c". Here's a little example:
> > Examples:
> >   (define p (make-parameter any/c))
> >   (define c (dynamic/c string? p number?))
> >   > (contract c "123" 'pos 'neg)
> >   pos broke the contract
> >     (dynamic
> >      string?
> >      #<procedure:parameter-procedure>
> >      number?)
> >    on eval:5:0; expected <number?>, given: "123"
> >   > (p (coerce/c string->number))
> >   > (contract c "123" 'pos 'neg)
> >   123
> >   > (contract c "123a" 'pos 'neg)
> >   pos broke the contract
> >     (dynamic
> >      string?
> >      #<procedure:parameter-procedure>
> >      number?)
> >    on eval:8:0; Coercion failed
> > The Web Server will define response/c as (dynamic/c any/c
> current-response/c
> > response?) and provide the current-response/c parameter for
> customization.
> > The default will be no coercion, but Xexpr conversion will be easily
> > accessible. A compatibility library will automatically set
> > current-response/c appropriately.
> > Attached is the new compatibility README.
> > I hope this will satisfy all.
> > Jay
> >
> > --
> > Jay McCarthy <jay at cs.byu.edu>
> > Assistant Professor / Brigham Young University
> > http://faculty.cs.byu.edu/~jay
> >
> > "The glory of God is Intelligence" - D&C 93
> >
> > _________________________________________________
> >  For list-related administrative tasks:
> >  http://lists.racket-lang.org/listinfo/dev
> >
>



-- 
Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University
http://faculty.cs.byu.edu/~jay

"The glory of God is Intelligence" - D&C 93
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