throws_propagation.swift

func id<T>(_ v: T) -> T { v }

func produceError() throws {}


// throws version

func f(_ a: () throws -> Void) rethrows { try a() }

f { }
try f { try produceError() }
try id(f)({ }) // Never `throw` but need `try` 😢
try id(f)({ try produceError() })

// Result version

func g<E>(_ a: () -> Result<Void, E>) -> Result<Void, E> { a() }

g { Result<Void, Never>.success(()) }      // Result<Void, Never>
g { Result { try produceError() } }        // Result<Void, Error>
id(g)({ Result<Void, Never>.success(()) }) // Result<Void, Never> 😎
id(g)({ Result { try produceError() } })   // Result<Void, Error>