What characters valid Kotlin identifiers? Some unicode characters are allowed without backtick-escap...

# mathematics

[breandan]

What characters valid Kotlin identifiers? Some unicode characters are allowed without backtick-escaping. For example val ε = 0.03 is a valid statement, but val ∇ = 0.03 is not.

[breandan]

Apparently it allows symbols from Unicode character categories Lu, Ll, Lt, Lm, Lo, Nl and Nd. The lexical grammar is defined here: https://github.com/JetBrains/kotlin-spec/blob/master/kotlin-spec.asc#42-lexical-grammar

[gildor]

You also can use backtickes:

val `∇` = 0.03

[breandan]

Yeah, but are also some restrictions on characters you can put inside backticks