Passing locale into a RegexBuilder

Question

I am building a tokeniser, and would like to represent this as a struct, passing in a locale.

Here's the gist of what I want to write:

struct Tokeniser {

    private let locale: Locale
    private let integerRegex: Regex

    init(locale: Locale) {
        self.locale: Locale
        self.integerRegex = Regex {
            Capture {
                .localizedInteger(locale: locale)
            } transform: {
                Token.number($0)
            }
        }
    }

    func parse(text: String) -> Token {
        if let match = try integerRegex.firstMatch(in: text) {
            //... other code here
        }
    }

    \\...other code here
}

As Regex is generic the compiler suggests to set the integerRegex's type to Regex<Any>, but this triggers another set of compiler issues that I have not been able to figure out what the type should be. So then I tried to write something like this (inspired by SwiftUI):

var integerRegex: some Regex {
    Capture {
        .localizedInteger(locale: locale)
    } transform: {
        Token.number($0)
    }
}

But again, the compiler prompts me to enter Regex.

The only way I have to be able to get the struct to compiler is to create lazy variables, which then have the side effect that I have to mark my functions as mutable, which have downstream issues when they are called from with SwiftUI structs.

    lazy var integerRegex = Regex {
        Capture {
            .localizedInteger(locale: locale)
        }
    }

    mutating func parse(text: String) -> Token {
        if let match = try integerRegex.firstMatch(in: text) {

        }
    }

How should I code this?