[plt-scheme] integer-in Contract
I assume the code generated to check the (integer-in 1 10) contract is
similar to what would be used for (and/c integer? exact? (>=/c 1) (<=/c
10)). In which case the integerness and exactness of the arguments 1 and 10
aren't important, just their real values. Should the exact integer
constraint on integer-in parameters be that strict?
Also, even if the exact integer constraint is deemed correct, would the use
of -inf.0 (as the first argument) or +inf.0 (as the second argument) allow
an efficient short cutting of the lower or upper bounds? I.e. (integer-in 1
+inf.0) would generate equivalent code to (and/c integer? exact? (>=/c 1))
but would not generate the upper limit test (<=/c +inf.0).
Just some thoughts.
Doug
On 8/14/07, Robby Findler <robby at cs.uchicago.edu> wrote:
>
> I've fixed the docs -- thanks for pointing that out!
>
> As far as the contract below goes, I'd guess I'd write:
>
> (and/c integer? (>=/c 1))
>
> to match the old behavior or:
>
> (and/c integer? exact? (>=/c 1))
>
> if you wanted exact integers.
>
> Robby
>
> On 8/14/07, Doug Williams <m.douglas.williams at gmail.com> wrote:
> > I am testing my collections on the new V371 release candidate and
> > encountered what appears to be a change in the integer-in contract. I
> have
> > often used (integer-in 1 +inf.0) as a contract for a positive
> integer. With
> > V371 this now gives an error "integer-in: expected two exact integers as
> > arguments, got 1 and +inf.0)". I can understand the change, but I also
> like
> > the convenience of using infinities as arguments here. Would it
> possible to
> > change integer-in so that it allows - inf.0 as the first argument and
> +inf.0
> > as the second? Or add a positive-integer/c contract that is similar to
> > natural-number/c?
> > I assume the best alternative now is to use (and/c natural-number/c (</c
> > 0)), but I really think (integer-in 1 +inf.0) matches the abstraction
> > better.
> > Is there a standard way that others use to denote a contract for a
> positive
> > integer?
> > By the way, the documentation still says integer-in takes two numbers as
> > arguments and should probably be updated to say two integers. There
> might
> > be a similar problem with the documentation for real-in that should
> limit it
> > to real numbers. I guess those are kind of nits.
> > Doug
> >
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> >
> >
>
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