[plt-scheme] Describe Function

Is there a way to write normal scheme code, then (once check-proofed) change
a value somewhere and make it use all the unsafe ops, preferably even at
DrScheme core?
I wonder how much faster the code could get.

(Just thinking about a possible trade-off: a macro that switches between
safe and unsafe locally.)

Laurent

On Wed, Nov 11, 2009 at 02:06, Robby Findler <robby at eecs.northwestern.edu>wrote:

> Those ones don't work on everything (fixnums, for example, altho that
> may be the only thing) and probably the guarantees of the behavior of
> those is less. And, of course, they are unsafe. :)
>
> Robby
>
> On Tue, Nov 10, 2009 at 5:57 PM, Doug Williams
> <m.douglas.williams at gmail.com> wrote:
> > Oh, there is an unsafe-vector-set! - and unsafe-struct-ref and set!.
> >
> > On Tue, Nov 10, 2009 at 4:51 PM, Doug Williams
> > <m.douglas.williams at gmail.com> wrote:
> >>
> >> Instead of the 'everything is a struct' view, you could also use an
> >> 'everything is a vector view' and with unsafe-vector-ref take things
> apart -
> >> even when they are opaque.
> >>
> >> (require scheme/unsafe/ops)
> >>
> >> (define-struct s (a b c))
> >>
> >> (define s1 (make-s 1 3 5))
> >>
> >> s1 -> #<s>
> >> (unsafe-vector-ref s1 0) -> #<struct-type:s>
> >> (unsafe-vector-ref s1 1) -> 1
> >> (unsafe-vector-ref s1 2) -> 3
> >> (unsafe-vector-ref s1 3) -> 5
> >>
> >> I assume that as long as I stay within the bounds of the underlying
> >> representation (and probably sometimes even if I don't - negative
> indices
> >> are allowed), unsafe-vector-ref will give gladly me the pieces. At least
> >> there is no unsafe-vector-set!
> >>
> >> Doug
> >>
> >> On Tue, Nov 10, 2009 at 11:29 AM, Doug Williams
> >> <m.douglas.williams at gmail.com> wrote:
> >>>
> >>> Sounds good. I was just thinking that a lower level implementation
> could
> >>> avoid the need to create a vector just to get the variant. But for my
> code
> >>> it's no big deal.
> >>>
> >>> On Tue, Nov 10, 2009 at 11:21 AM, Robby Findler
> >>> <robby at eecs.northwestern.edu> wrote:
> >>>>
> >>>> On Tue, Nov 10, 2009 at 12:18 PM, Doug Williams
> >>>> <m.douglas.williams at gmail.com> wrote:
> >>>> > Robby,
> >>>> >
> >>>> > I am going to add your variant procedure to the describe collection.
> >>>>
> >>>> Great!
> >>>>
> >>>> > Are you
> >>>> > happy with the name 'variant' and the contract (-> any/c symbol?)?
> >>>>
> >>>> Yes. (You may want to use substring isntead of regexp-match.)
> >>>>
> >>>> > What is
> >>>> > the relationship between this and object-name?
> >>>>
> >>>> Nothing really. object-name is per-object (and not everything has a
> >>>> name).
> >>>>
> >>>> >  It seems that for actual
> >>>> > structs they return the same value. Would it make sense to change
> >>>> > object-name to return the same value as variant in those cases where
> >>>> > it
> >>>> > (i.e., object-name) returns #f? This would trivially make this
> >>>> > functionality
> >>>> > available in #lang scheme, which seems to be a good thing.
> >>>>
> >>>> I don't think that that change is really a good idea at this point.
> >>>> Probably would break lots of stuff.
> >>>>
> >>>> Robby
> >>>>
> >>>> > Doug
> >>>> >
> >>>> > On Tue, Nov 10, 2009 at 7:43 AM, Robby Findler
> >>>> > <robby at eecs.northwestern.edu>
> >>>> > wrote:
> >>>> >>
> >>>> >> On Tue, Nov 10, 2009 at 8:41 AM, Dave Herman <dherman at ccs.neu.edu>
> >>>> >> wrote:
> >>>> >> >> This probably doesn't help Doug, but here is another way to
> define
> >>>> >> >> the
> >>>> >> >> function linked above:
> >>>> >> >
> >>>> >> > That's neat, thanks! Has struct->vector always worked on
> >>>> >> > non-structs?
> >>>> >>
> >>>> >> I'm not sure about always, but at some point a while ago, Matthew
> >>>> >> decided that all values are structs (in the sense that you could
> have
> >>>> >> implemented everything with structs and scope, etc even if some of
> >>>> >> them are implemented in C) and adapted the primitives to make them
> >>>> >> behave accordingly.
> >>>> >>
> >>>> >> Robby
> >>>> >
> >>>> >
> >>>
> >>
> >
> >
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>
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