Interpolation.swift

struct Entry: ExpressibleByStringInterpolation {
    // typealias StringInterpolation = EntryInterpolation
    
    private(set) var value: String
    
    init(stringLiteral value: String) {
        self.value = value
    }
    
    init(stringInterpolation: EntryInterpolation) {
        self.value = stringInterpolation.values.joined()
    }
}

struct EntryInterpolation: StringInterpolationProtocol {
    private(set) var values: [String]
    
    init(literalCapacity: Int, interpolationCount: Int) {
        self.values = []
    }
    
    mutating func appendLiteral(_ literal: StringLiteralType) {
        values.append(literal)
    }
}