I have never tried to implement a “stream” in Swift, so I am not sure if there is an easy way to do it…. but I don’t see a collection of type stream as I have in Scala.
http://www.scala-lang.org/api/current/index.html#scala.collection.immutable.Stream <http://www.scala-lang.org/api/current/index.html#scala.collection.immutable.Stream> > On 2015-12-30, at 7:39:54, Dave Abrahams <dabrah...@apple.com> wrote: > > >> On Dec 29, 2015, at 4:29 PM, Craig Cruden <ccru...@novafore.com >> <mailto:ccru...@novafore.com>> wrote: >> >>> Could you define what you mean by “stream support?” Whatever it is, I >>> doubt simply adding an infinitely-repeating sequence type is enough to get >>> you there. >> >> >> I can guess — but it is only a guess. >> >> A function defines an infinite “set” of values (like the digits of pi). A >> stream is just a special type of traversable (lazy) which does not evaluate >> until asked for the next in a sequence of the set. A function defined in a >> stream will thus only continue calculating next digits when asked for them. >> Similarly you could have a collection (head/tail) and you ask for the head >> and you get it, but the rest (tail) is just the tail as a whole and none of >> the values in it are really defined until you traverse down to the next head >> of the rest of the tail. Once it is evaluated it is stored in memory for >> future evaluations. If you were to fully evaluate the function it would >> never finish, and if it were to finish — you would probably run out of >> memory. > > Yes, I understand the usual concept of a “stream," but it doesn’t help me > understand what stream *support* entails. > > -Dave >
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