One thing that would solve a lot of this issue would be if the pregexp
syntax added support for named captures as in Perl and the PCRE library
that exports them. Something like this:
#lang at-exp racket
(define str "[04, foo, 03.5]")
(define pat @(pregexp
@~a{\[(?<item-num>\d+),\s*(?<name>\w+),\s*(?<price>[.\d]+)}))
(match str
[pat (println (~a "item name: " name ", number: " item-num ", price: $"
price))])
Alternatively, if 'match' made the results of a successful regexp test
available to the bodies on the RHS then you could do the same thing by
accessing the result list. Perhaps if match would allow the RHS to be a
function?
(match "foo"
[#px"oo.+(.)" (lambda (res) (println (~a "Regexp match results were: "
res)))])
Output:
'("oobar" "r")
On Fri, Jul 21, 2017 at 6:20 PM, Gustavo Massaccesi <gust...@oma.org.ar>
wrote:
> IIRC the previous discussion, one way to fix this problem is to make a
> package that can parse strings easily using a C like format, like the
> expected in the contests. Something like
>
> #lang racket
> (require compatibility/scanf)
>
> (let-values ([(x y) (scanf "%d %d" (read-line))])
> (display (+ x y)))
>
> It's not very idiomatic, but it may be helpful for this particular use.
>
> IIRC another problem is that in the contest you are not allowed to
> install the packages you wish, you can only use the default
> installation. But I think that the idea is not to allow everything in
> the default installation.
>
>
> So my proposal is to add another installation mode for Racket
>
> * minimal: Only the core and some minimal packages
> * main: The normal set of packages, (only idiomatic) batteries included.
> * community (new): everything in the ring 1, including the kitchen
> sink. With a minimal curation and a minimal baseline of features (like
> no breaking the installation). (And a compatible license.) The
> packages may disappear/change/reappear from version to version. All
> the additional packages may be experimental/unstable/unsuported.
>
> Is this acceptable in a competition?
> Is this acceptable as another "official" Racket distribution?
>
> Gustavo
>
>
>
> On Fri, Jul 21, 2017 at 4:35 PM, Brian Mastenbrook
> <br...@mastenbrook.net> wrote:
> > On 07/21/2017 12:49 PM, Matthias Felleisen wrote:
> >>
> >>
> >>> On Jul 21, 2017, at 1:56 AM, Sorawee Porncharoenwase
> >>> <sorawee_porncharoenw...@brown.edu> wrote:
> >>>
> >>> Sorry for reviving an old thread. As someone who did a lot of
> programming
> >>> competition in the past, I can totally see why IO in Racket is
> difficult. As
> >>> mark.engelberg said, the goal is to solve as many problems as possible.
> >>> After the competition is over, it's over. No one is going to care about
> >>> maintainability or good coding practice if it makes coding slower.
> >>
> >>
> >> Which is why I think programming competitions are a direct attempt to
> >> undermine computer science and computer-science education.
> >>
> >> Having said that, if you want to use Racket for competitions, you and
> Mark
> >> Engelberg should get together and produce a high-utility IO library. We
> can
> >> then include it in the distribution.
> >
> >
> > Just as a counterpoint, I have this kind of ad-hoc
> parse-this-produce-that
> > problem all the time in the "real" world. When the logic of the problem
> is
> > sufficiently complex I'll swallow the overhead of doing it in Racket, or
> > I'll use Perl to transform the input into something I can read in
> Racket. It
> > would be nice to have an I/O library that made it easy, but I don't have
> any
> > specific thoughts about how to do that.
> >
> > I don't think computer science education should ignore this kind of
> problem
> > though. It's very important to teach students how to solve problems
> > methodically with a design recipe, how to collaborate with others, and
> how
> > to reason about their programs. But it's also important that programmers
> > (and also or even especially those who don't program for a living) be
> > comfortable with using the machine to solve or automate the solution to
> > one-off problems that would otherwise require a lot of manual fiddling
> with
> > data. Being fluent with this kind of programing gives people the
> confidence
> > they need to solve smaller problems or explore potential solutions to
> large
> > problems in an unstructured manner before tackling the methodical,
> "right"
> > solution.
> >
> > --
> > Brian Mastenbrook
> > br...@mastenbrook.net
> > https://brian.mastenbrook.net/
> >
> >
> > --
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