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29 lines
507 B
Swift
29 lines
507 B
Swift
// Copyright © 2015 GitHub. All rights reserved.
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public enum Cofree<A, B> {
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indirect case Unroll(B, Syntax<Cofree, A>)
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public var unwrap: Syntax<Cofree, A> {
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switch self {
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case let .Unroll(_, rest):
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return rest
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}
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}
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}
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// MARK: - Comonad
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extension Cofree {
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public var extract: B {
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switch self {
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case let .Unroll(b, _):
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return b
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}
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}
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func extend<Other>(transform: Cofree -> Other) -> Cofree<A, Other> {
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return .Unroll(transform(self), unwrap.map { $0.extend(transform) })
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}
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}
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