Is there any documentation that clearly explains the difference between Kotlin's

Regex

vs. Java's

Pattern

?

You mean regarding the regex syntax?

Kotlin's

Regex

class is essentially a multiplatform wrapper around each platform's standard Regex implementation. As such, the specific pattern format may be slightly different between different targets, but on JVM,

Regex

delegates to

java.util.regex.Pattern

. So the only difference between

Regex

and

Pattern

is the actual Kotlin API, not the pattern syntax itself https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/-regex/

as the link says, Kotlin Regex syntax is Java Pattern on JVM, JS RegExp on JS, and I'm not sure what on native (it's not documented)

Native was implemented from scratch to match JVM iirc.

I see harmony_regex tests in the kotlin.git/kotlin-native so that checks out

yeah, PCRE would have been my guess too

Thanks @Casey Brooks: I was aware that Regex (on JVM) used the Java Pattern syntax, but it wasn't clear from the text that Regex = Pattern.

Represents a compiled regular expression. Provides functions to match strings in text with a pattern, replace the found occurrences and split text around matches.

For pattern syntax reference see Pattern.