> On Nov 24, 2017, at 4:15 PM, Chris Lattner <[email protected]> wrote:
>
>>
>> than the same type having a collection of named matches using the usual Perl
>> syntax?
>>
>> if case /(?<firstName>[a-zA-Z]+) (?<lastName>[a-zA-Z]+)/ = getSomeString()
>> {
>> print(Regex.captured["firstName"], Regex.captured["lastName"])
>> }
>
> Personally, I really don’t like this. It turns a structured problem into one
> that violates DRY and loses the structure inherent in the solution. Also,
> while theoretically the dictionary could be optimized away, in practice that
> would be difficult to do without heroics.
>
One other minor and obscure point: if the compiler is aware of the regex
grammar it can properly type the matches, I can imagine the following cases:
if case /(let name: [a-zA-Z]+) (let count: Int)/ = getSomeString() {
print(name, count)
}
-> name has type String, count has type Int (and matches [0-9]+)
if case /(let name: [a-zA-Z]+)? (let count: Int)/ = getSomeString() {
print(name, count)
}
-> name has type String?
if case /(let name: [a-zA-Z]+)* (let count: Int)/ = getSomeString() {
print(name, count)
}
-> name has type [String]
etc. Even if we don’t have a “default regex” for types, it would still be
awesome to be able to write:
if case /(let name: [a-zA-Z]+) (let count: Int: [0-9]+)/ = getSomeString() {
print(name, count)
}
and have that transparently invoke and check the Int?(string) failable
initializer.
-Chris
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