eMdOS

How to use a .xcconfig file and a .plist file with SPM

Worth a read for some more context.

Create a Package.xcconfig file

Create the file in the root of the project (where your Package.swift file lives as well), and use the following contents:

/// Package.xcconfig

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let elements: [String] = ["A", "B", "C", "D", "E", "F", "G", "H", "I"]

let chunk_1 = elements[...2].joined()
let chunk_2 = elements[3...5].joined()
let chunk_3 = elements[6...].joined()

concat(elements) == chunk_1 <> chunk_2 <> chunk_3
concat(elements) == concat([chunk_1, chunk_2, chunk_3])

eMdOS

concat(["A", "B", "C"]) == [String](arrayLiteral: "A", "B", "C").reduce("", <>)

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public func concat<M: Monoid>(_ elements: [M]) -> M {
    elements.reduce(.empty, <>)
}

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extension String: Monoid {
    public static let empty: String = ""
}

extension Array: Monoid {
    public static var empty: Array { [] }
}

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// left identity
[] + ["A"] // = ["A"]
// right identity
["A"] + [] // = ["A"]

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// left identity
"" + "A" // = "A"
// right identity
"A" + "" // = "A"

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public protocol Monoid: Semigroup {
    static var empty: Self { get }
}

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XCTAssert(
    AssociativeLaw<String>.verify(a: "hello", b: " ", c: "world!")
)

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public extension AssociativeLaw where Element: Semigroup {
    ///
    /// It verifies if the set of elements are **associative** through Semigroup's composition (`<>`).
    ///
    /// The `<>` operator is used to express associativity in an abstract way.
    /// This is because elements can either be associative through *addition* (`+`) or through *multiplication* (`*`).
    ///
    /// - Parameters:
    ///   - a: The first semigroup element
    ///   - b: The second semigroup element