[swift-evolution] [Pitch] New Version of Array Proposal

[Taylor Swift]

This proposal gives FSAs their own literal syntax. You write [; 3, 5] to
make a FSA, not [3, 5].

On Sun, Jul 23, 2017 at 11:54 PM, David Sweeris <davesweeris at mac.com> wrote:

>
> On Jul 23, 2017, at 8:32 PM, Taylor Swift <kelvin13ma at gmail.com> wrote:
>
> On Sun, Jul 23, 2017 at 5:48 PM, David Sweeris <davesweeris at mac.com>
> wrote:
>
>>
>> On Jul 23, 2017, at 12:18, Taylor Swift <kelvin13ma at gmail.com> wrote:
>>
>> On Sun, Jul 23, 2017 at 2:21 PM, David Sweeris <davesweeris at mac.com>
>> wrote:
>>
>>>
>>> On Jul 23, 2017, at 09:08, Taylor Swift <kelvin13ma at gmail.com> wrote:
>>>
>>> let fsa:[2 * Int] = [2 * 5, 3] // [10, 3] ???
>>>
>>>
>>> Correct. If you wanted a multidimensional array, that'd be written "let
>>> nestedFSA: [2*[5*Int]]". Or, speculating a bit, I suppose maybe "let
>>> nestedFSA: [[5*Int]*2]", if we wanted there to be a column-major option.
>>> IMHO all those read better than this proposal's syntax.
>>>
>>>
>>>
>> No, what I’m saying is does the phrase “[2 * 5, 3]” mean a fixed size
>> array of length two and with the elements 5 and 3, or a flexible sized
>> array with two elements 10 and 3? This is v confusing and difficult to
>> read, especially when you have actual multiplications going on such as
>>
>> let fsa:[2 * Int] = [2 * 3 * 5, 3] // [15, 3] ???
>>
>>
>> That's... huh? To me, "[2 * 3 * 5, 3]" should obviously evaluate to
>> "[30, 3]". How are you getting that "[2*5*3, 3]" could be a 2-element FSA
>> containing 15 and 3? Are you suggesting that instead of "[value * value *
>> value, value]", it could be parsed as "[modifier value * value, value]"
>> (with `modifier` being "2 *")? To me, that syntax would *strongly*
>> suggest that the modifier only applies to the first element of the array,
>> which would mean the only other option for parsing it would be equivalent
>> to "[[3, 5], 3]", which is neither a match for fsa's type, nor a
>> semantically valid array (the elements have to be the same type), nor a
>> syntactically valid array (the nested array in the first element is missing
>> its "[]").
>>
>>
> Well, that *is* the syntax you’re proposing right? What comes on the left
> of the asterisk is the FSA dimensions, and what comes to the right is the
> FSA elements.
>
>
> No, the *type* of the FSA's elements is what comes to the right: "[count
> * *Type*]". I don't recall any discussion around the value side of
> things, so I'd guess they would've just used the existing array literal
> syntax, "let fsa: [2*[2*Int]] = [[0, 1], [2, 3]]".
>
> - Dave Sweeris
>
>
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