[racket-dev] [plt] Push #26536: master branch updated

If you're writing a higher-order tool like curry or negate, and want to
produce a meaningful arity for its result, you're going to need some
explicit representation of arity to manipulate, e.g. subtract one from
every number in the list after partially applying to a single argument.
Once users are manipulating the value, you either need to accept
non-normalized inputs, or you need an abstract datatype to encapsulate the
whole thing that enforces normalization.  Since we already have list-based
arities in our interfaces, I continued with the interface as it was.  I did
think of combining the two arity-includes? functions, I wasn't sure whether
the extra overloading would make things clearer or more confused.  I can
see doing it either way.

Carl Eastlund


On Thu, Apr 11, 2013 at 11:33 AM, Eli Barzilay <eli at barzilay.org> wrote:

> OK, that's a valid use case -- but isn't it better for both of these
> uses to just use some combinator for arities that generates a properly
> normalized arity instead of constructing lists and explicitly
> normalizing them?
>
> It's just that the interface looks very complex now.  Some obvious
> things:
>
> * `procedure-arity-includes?' vs `arity-includes?'
>   (but it's the second that compares two procedures...  I'd just make
>   the first accept a procedure to avoid this unfortunate naming.)
>
> * `normalize-arity', `normalized-arity?', `arity=?'
>   (go away with a combinator, the last one gets replaced with
>   `equal?')
>
>
>
> A few minutes ago, Carl Eastlund wrote:
> > If we want people to be able to create higher-order functions with
> > precise arities via procedure-reduce-arity, for instance, we need to
> > provide tools for manipulating arity values.  Manipulating them is
> > also useful for producing error messages that describe the arity of
> > procedure values.  I don't see any reason to close this stuff off,
> > when it's the one useful, non-opaque aspect of procedure values.
> >
> > Carl Eastlund
> >
> > On Thu, Apr 11, 2013 at 11:13 AM, Eli Barzilay <eli at barzilay.org> wrote:
> >
> >     Is there a real need to make this whole thing a public interface?
>  I'd
> >     think that a general direction is to move away from making it public
> >     (ie, remove the ability to create an arity value), and this seems to
> >     add a pretty big chunk of stuff in the opposite direction.
> >
> >     About two weeks ago, cce at racket-lang.org wrote:
> >     > cce has updated `master' from 6e40caa7e2 to df00bbb194.
> >     >   http://git.racket-lang.org/plt/6e40caa7e2..df00bbb194
> >     >
> >     > =====[ 7 Commits
> ]======================================================
> >     > Directory summary:
> >     >   21.0% collects/racket/private/
> >     >   21.5% collects/racket/
> >     >   26.4% collects/scribblings/reference/
> >     >   30.9% collects/tests/racket/
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > 59b1e32 Carl Eastlund <cce at racket-lang.org> 2013-03-30 11:45
> >     > :
> >     > | Changed normalize-arity to coalesce arity-at-least with adjacent
> >     numbers.
> >     > |
> >     > | For instance, (normalize-arity (list 1 (arity-at-least 2))) now
> >     produces
> >     > | (arity-at-least 1).  The implementation and the tests for
> >     normalize-arity both
> >     > | reflect this change.  The randomized tests now also check that
> the
> >     output
> >     > | represents the same arity as the input.
> >     > :
> >     >   M collects/racket/private/norm-arity.rkt |  82
> +++++++++++++---------
> >     >   M collects/tests/racket/basic.rktl       | 112
> >     +++++++++++++++++++++++++-----
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > e356c66 Carl Eastlund <cce at racket-lang.org> 2013-03-30 11:49
> >     > :
> >     > | Re-provide normalize-arity from racket/function.
> >     > :
> >     >   M collects/racket/function.rkt | 4 ++--
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > 4dd011a Carl Eastlund <cce at racket-lang.org> 2013-03-30 15:49
> >     > :
> >     > | Added documentation for normalize-arity.
> >     > :
> >     >   M collects/scribblings/reference/procedures.scrbl | 42
> >     ++++++++++++++++++----
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > 636f8a9 Carl Eastlund <cce at racket-lang.org> 2013-03-30 21:04
> >     > :
> >     > | Moved normalized-arity?, arity=?, and arity-includes? into
> racket/
> >     function.
> >     > :
> >     >   M collects/racket/function.rkt     | 94
> >     +++++++++++++++++++++++++++++++++++-
> >     >   M collects/tests/racket/basic.rktl | 96
> >     +------------------------------------
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > aaa99d5 Carl Eastlund <cce at racket-lang.org> 2013-03-30 21:05
> >     > :
> >     > | Documented normalized-arity?, arity=?, and arity-includes?.
> >     > :
> >     >   M collects/scribblings/reference/procedures.scrbl | 87
> >     +++++++++++++++++++---
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > f509420 Carl Eastlund <cce at racket-lang.org> 2013-03-30 17:12
> >     > :
> >     > | Removed unnecessary duplication of normalize-arity.
> >     > :
> >     >   M collects/tests/racket/fixnum.rktl | 21 ++-------------------
> >     >
> >     > ~~~~~~~~~~
> >     >
> >     > df00bbb Carl Eastlund <cce at racket-lang.org> 2013-03-31 10:34
> >     > :
> >     > | Updated contracts for arity-related functions.
> >     > |
> >     > | Added contract checking to arity=?, arity-includes?, and
> >     normalized-arity.
> >     > | Removed contract checking from normalize-arity to make it a total
> >     predicate.
> >     > | Updated documentation for normalize-arity to reflect this change.
> >     > :
> >     >   M collects/racket/function.rkt                    | 21
> >     ++++++++++++++++-----
> >     >   M collects/racket/private/norm-arity.rkt          |  2 ++
> >     >   M collects/scribblings/reference/procedures.scrbl | 13
> ++++++-------
> >
> >     --
> >               ((lambda (x) (x x)) (lambda (x) (x x)))          Eli
> Barzilay:
> >                         http://barzilay.org/                   Maze is
> Life!
> >
>
> --
>           ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
>                     http://barzilay.org/                   Maze is Life!
>
>
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