Re: [swift-evolution] About the PermutationGenerator

Thank you for this. Also, the book states: "SequenceType makes no requirement on conforming types regarding whether they will be destructively "consumed" by iteration. To ensure non-destructive iteration, constrain your sequence to CollectionType." Your magic DWIM Swift has generators (you call

Re: [swift-evolution] About the PermutationGenerator

> On Jan 6, 2016, at 11:37 AM, Jordan Rose via swift-evolution > wrote: > > I've bounced this idea off of Dave and Dmitri internally, so might as well > put it out publicly: > > In Magic DWIM Swift, there would only be two types that you'd ever conform > to: a destructive iteration type (tod

Re: [swift-evolution] About the PermutationGenerator

I've bounced this idea off of Dave and Dmitri internally, so might as well put it out publicly: In Magic DWIM Swift, there would only be two types that you'd ever conform to: a destructive iteration type (today's "Generator"), and a multi-pass indexed type (today's "Collection"). Some operation

Re: [swift-evolution] About the PermutationGenerator

I see what you’ve done, now, after diffing your code with mine. That’s a very nice improvement; it generalizes to cover more Sequences and doesn’t require an Equatable generator. Great job! > On Dec 31, 2015, at 9:30 PM, Susan Cheng wrote: > > I didn't explain correctly. > > let's take this

Re: [swift-evolution] About the PermutationGenerator

I didn't explain correctly. let's take this: let c = Multipass(Fib(a: 1, b: -1, limit: 10)) this sequences should have results with [1, -1, 0, -1, -1, ...] So is c.startIndex.successor() equal to c.startIndex.successor().successor().successor()?? Dave Abrahams 於 2016年1月1日星期五 寫道： > > On Dec 31

Re: [swift-evolution] About the PermutationGenerator

> On Dec 31, 2015, at 8:22 PM, 鄭齊峯 via swift-evolution > wrote: > > if you try my modification, it will crash. Only because your Sequence genereates an arithmetic underflow. I don’t understand what point you’re trying to make > > struct Fib : SequenceType { > > var a: Int > var

Re: [swift-evolution] About the PermutationGenerator

if you try my modification, it will crash. struct Fib : SequenceType { var a: Int var b: Int var limit: Int func generate() -> FibGenerator { return Generator(a: a, b: b, limit: limit) } } let c = Multipass(Fib(a: 1, b: -1, limit: 10)) A SequenceType be

Re: [swift-evolution] About the PermutationGenerator

> On Dec 31, 2015, at 7:46 PM, Susan Cheng wrote: > > > How GeneratorType confirm to Equatable?? I don’t understand the question. In the code I posted there’s a working example of how a GeneratorType model can conform to Equatable.. > > struct Fib : SequenceType { > > var a: Int >

Re: [swift-evolution] About the PermutationGenerator

> On Dec 31, 2015, at 1:02 PM, Dave Abrahams via swift-evolution > wrote: > >> >> On Dec 31, 2015, at 10:52 AM, Donnacha Oisín Kidney > > wrote: >> >> Just to add to that, it’s always seemed strange to me that to signify your >> sequence is multi-pass (i.e., to

Re: [swift-evolution] About the PermutationGenerator

How GeneratorType confirm to Equatable?? struct Fib : SequenceType { var a: Int var b: Int var limit: Int func generate() -> FibGenerator { return Generator(a: a, b: b, limit: limit) } } let c = Multipass(Fib(a: 1, b: -1, limit: 10)) -Susan 2016-01-01 11:17 GMT+0

Re: [swift-evolution] About the PermutationGenerator

> On Dec 31, 2015, at 10:52 AM, Donnacha Oisín Kidney > wrote: > > Just to add to that, it’s always seemed strange to me that to signify your > sequence is multi-pass (i.e., to make it conform to CollectionType) you have > to have it conform to Indexable. FWIW, Indexable is an implementatio

Re: [swift-evolution] About the PermutationGenerator

> On Dec 31, 2015, at 9:52 AM, Erica Sadun wrote: > > I'm trying to work them out, so it's still muddled. > > Right now, I think SequenceType is better described as CollectionWalkType Why do you say so? > but that's kind of (1) a mouthful and (2) not entirely accurate. > > Moving back a ste

Re: [swift-evolution] About the PermutationGenerator

Just to add to that, it’s always seemed strange to me that to signify your sequence is multi-pass (i.e., to make it conform to CollectionType) you have to have it conform to Indexable. > On 31 Dec 2015, at 17:52, Erica Sadun via swift-evolution > wrote: > > I'm trying to work them out, so it

Re: [swift-evolution] About the PermutationGenerator

I'm trying to work them out, so it's still muddled. Right now, I think SequenceType is better described as CollectionWalkType but that's kind of (1) a mouthful and (2) not entirely accurate. Moving back a step: SequenceType is defined as: "A type that can be iterated with a `for`...`in` loop."

Re: [swift-evolution] About the PermutationGenerator

> On Dec 31, 2015, at 9:05 AM, Erica Sadun via swift-evolution > wrote: > > It does seem that in Swift the concepts of collection, sequence, permutation, > stream, etc are a bit muddled. This is a pretty vague critique. Do you have specifics, and suggestions that address them? > > -- E >

Re: [swift-evolution] About the PermutationGenerator

It does seem that in Swift the concepts of collection, sequence, permutation, stream, etc are a bit muddled. -- E > On Dec 31, 2015, at 6:51 AM, Tino Heth via swift-evolution > wrote: > >> Those are collections. Collections can be iterated over multiple times. > Speaking of the Fibonacci-nu

Re: [swift-evolution] About the PermutationGenerator

sequence can have more methods with it, we can find first five values of a sequence. but we don't do this with a generator struct Fibonacci: SequenceType { var first, second: Int func generate() -> AnyGenerator { var a = first var b = second return any

Re: [swift-evolution] About the PermutationGenerator

On Thu, Dec 31, 2015 at 3:51 PM, Tino Heth <2...@gmx.de> wrote: >> Those are collections. Collections can be iterated over multiple times. > Speaking of the Fibonacci-numbers: > Sure we can write an algorithm that iterates over them several times — it > just won't ever finish the first iteration

Re: [swift-evolution] About the PermutationGenerator

On Thu, Dec 31, 2015 at 3:36 PM, Susan Cheng wrote: > I don't think so. > > As we don't say "Fibonacci collection", we know Fibonacci numbers are in > order. But we can't tell the number immediately if I asked a specific index > of Fibonacci sequence. The only way is calculate the sequence one by

Re: [swift-evolution] About the PermutationGenerator

> Those are collections. Collections can be iterated over multiple times. Speaking of the Fibonacci-numbers: Sure we can write an algorithm that iterates over them several times — it just won't ever finish the first iteration ;-) (only nitpicking — I just couldn't resist) Happy new year! ___

Re: [swift-evolution] About the PermutationGenerator

I don't think so. As we don't say "Fibonacci collection", we know Fibonacci numbers are in order. But we can't tell the number immediately if I asked a specific index of Fibonacci sequence. The only way is calculate the sequence one by one from start. So we need the collection, and collection do

Re: [swift-evolution] About the PermutationGenerator

On Thu, Dec 31, 2015 at 3:04 PM, Susan Cheng wrote: > yes for sequences are not immutable. I get confused. > > no for sequences should be definition of lists of values. Just like > Fibonacci sequence, we can calculate the values form the start of the > Fibonacci sequence one by one. But we are not

Re: [swift-evolution] About the PermutationGenerator

yes for sequences are not immutable. I get confused. no for sequences should be definition of lists of values. Just like Fibonacci sequence, we can calculate the values form the start of the Fibonacci sequence one by one. But we are not accessing the values of Fibonacci sequence. A socket can be

Re: [swift-evolution] About the PermutationGenerator

On Thu, Dec 31, 2015 at 2:01 PM, Susan Cheng via swift-evolution < swift-evolution@swift.org> wrote: > As I know SequenceType should have behaved as immutable structure and it > provides method to get a mutable GeneratorType which generates value from > start of sequence. Sequences are not immut

Re: [swift-evolution] About the PermutationGenerator

As I know SequenceType should have behaved as immutable structure and it provides method to get a mutable GeneratorType which generates value from start of sequence. But the PermutationGenerator break this rule, every time it changes it's state, it cannot get the generator with the start of sequenc

Re: [swift-evolution] About the PermutationGenerator

We have plenty of examples of GeneratorTypes that also conform to SequenceType. There's no harm in it, and it saves having to declare a separate type that consists solely of a generate() method that returns the generator. In fact, the stdlib automatically derives the generate() method for any Gener

[swift-evolution] About the PermutationGenerator

PermutationGenerator confuses me that it's confirm to both of SequenceType and GeneratorType. Should it replace by PermutationSequence and PermutationGenerator? Also, we should have a PermutationCollection because we can: public struct PermutationCollection : CollectionType { public type