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Comment by galaxyLogic | Hacker News Reader

2 RegExp problems:

1. You can not compose a bigger regexp out of smaller ones

2. A regexp can not "call" other regexps

To do regex matching efficiently, you need to compile the pattern before using it. That'd exclude dynamically "calling" other regex patterns. But bigger regex pattern strings can be composed from smaller regex pattern strings. You'd just need to do the composition before the compilation.

Also define blocks if all someone wants is to break the pattern up to make it more readable.

Great idea

I'm just thinking in JavaScript I can do this:

  let s =  "abc" + "def";

Why can't I do:

  let regExp = /abc/ + /def/;

If JavaScript (or some other) interpreter can turn /abc/ into a RegExp, why can't it do the same for

/abc/ + /def/

Swift has a RegexBuilder[1][2] interface, in addition to the usual string-ey interface that allows composition.

[1]: https://github.com/swiftlang/swift-evolution/blob/main/propo...

[2]: https://developer.apple.com/documentation/regexbuilder

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