[racket] taking from a generator, and a possible bug

From: Ray Racine (ray.racine at gmail.com)
Date: Sun Aug 19 20:17:59 EDT 2012

Plans for TR support for generic interfaces down the road?

(: add (All (K V [M <:  (Gen:Dict K V)])  M K V -> M))

On Sun, Aug 19, 2012 at 6:11 PM, Asumu Takikawa <asumu at ccs.neu.edu> wrote:

> On 2012-08-19 11:20:01 -0700, Ian Tegebo wrote:
> > Thanks for the clarification; I needed both `stream-cons` and
> > `in-producer` examples.  Also, your tone regarding the stream API
> > suggests there might be ongoing work and/or other interesting details.
> >  If so, could you elaborate?
> Sure. Vincent and I have been working on improving various aspects of
> generic operations in Racket. In 5.3, we introduced a general mechanism
> for defining a generic interface and implementing its methods (see
> `gen:stream` for streams, for example).
> We have some ideas floating around for introducing an extended generic
> interface for datatypes that are "buildable"[1]. That is, you'd provide a
> construction operation so that operations like map, filter, and so on
> could produce the same type of thing (whereas with streams and sequences
> now, they produce an "opaque" thing).
> This is still very much a work in progress, but hopefully we'll have
> something more concrete soon.
> Cheers,
> Asumu
> [1]: my understanding is that Scala provides this kind of functionality
>      with its generic package for collections:
> http://www.scala-lang.org/api/current/index.html#scala.collection.generic.package
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