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Having amazing string capabilities is more important now than ever. But that actually argues against including regex in the language syntax itself. You want reg

by SiVal 12y ago

Having amazing string capabilities is more important now than ever. But that actually argues against including regex in the language syntax itself. You want regular expressions to be able to evolve to become ever more powerful and useful. So just include a literal string type in the language itself--one that minimizes the need for escapes and can be used for all sorts of protocols--and use a regex library. The syntaxes of the library and the language can then evolve somewhat independently, and if it reaches a point where you need a non-backwards-compatible change in the regular expression syntax for some great new innovation, people who still need the old one can continue to import the old library, while others can import the new one. The freedom of technologies to work together yet evolve independently is an important "feature" that's worth protecting.

danudey 12y ago
Aside from these reasons, you also have the case of performance optimization. In Perl, for example, pretty much all string parsing (that I've ever seen done in Perl code) is done via regular expressions. Regular expressions in Perl are such a thing that most software I've used that uses regular expressions uses the Perl-compatible regular expression library (libpcre). The issue is that if you provide developers with a simple method of e.g. splitting a string using regular expressions, then they will always split their strings with regular expressions. This is rarely the most optimal way of doing it, however, and it requires more memory and more overhead than e.g. splitting a string by simply scanning it. The reason this is a problem for Swift in particular is mobile devices, where memory and CPU use is more costly than on desktop software. I don't think it's coincidence that all the languages I'm aware of which natively support regexes as part of the language syntax are interpreted/scripting languages where performance is not the language's primary concern (Python being one such language with this syntax notably absent), whereas the language that the grandparent comment listed for 'safer languages' which do not have regex literal support ("Java, C#, Go, Rust, Haskell, or to be charitable, C++") are all compiled languages where performance is assumed to be part of the primary concern for the language design and for developers in the language.
- benniw 12y ago
  "more memory and more overhead than e.g. splitting a string by simply scanning it." Regexes are simply scanning strings, they're just a more condensed syntax for specifying how the scanning should be done. And in interpreted languages, using the built-in regex feature (which can apply high-level optimizations) will virtually always give much better performance than implementing the same logic by manually looping over the string character-by-character with the language's interpreted for/while loops.

by SiVal 12y ago

danudey 12y ago

Aside from these reasons, you also have the case of performance optimization. In Perl, for example, pretty much all string parsing (that I've ever seen done in Perl code) is done via regular expressions. Regular expressions in Perl are such a thing that most software I've used that uses regular expressions uses the Perl-compatible regular expression library (libpcre). The issue is that if you provide developers with a simple method of e.g. splitting a string using regular expressions, then they will always split their strings with regular expressions. This is rarely the most optimal way of doing it, however, and it requires more memory and more overhead than e.g. splitting a string by simply scanning it. The reason this is a problem for Swift in particular is mobile devices, where memory and CPU use is more costly than on desktop software. I don't think it's coincidence that all the languages I'm aware of which natively support regexes as part of the language syntax are interpreted/scripting languages where performance is not the language's primary concern (Python being one such language with this syntax notably absent), whereas the language that the grandparent comment listed for 'safer languages' which do not have regex literal support ("Java, C#, Go, Rust, Haskell, or to be charitable, C++") are all compiled languages where performance is assumed to be part of the primary concern for the language design and for developers in the language.

benniw 12y ago
"more memory and more overhead than e.g. splitting a string by simply scanning it." Regexes are simply scanning strings, they're just a more condensed syntax for specifying how the scanning should be done. And in interpreted languages, using the built-in regex feature (which can apply high-level optimizations) will virtually always give much better performance than implementing the same logic by manually looping over the string character-by-character with the language's interpreted for/while loops.