Open
Description
| Previous ID | SR-2318 |
| Radar | rdar://problem/27808030 |
| Original Reporter | fabb (JIRA User) |
| Type | Bug |
Additional Detail from JIRA
| Votes | 0 |
| Component/s | Compiler |
| Labels | Bug, 3.0Regression, DiagnosticsQoI, TypeChecker |
| Assignee | None |
| Priority | Medium |
md5: 1f0ae6b06b963821044de344fd24bc8a
Issue Description:
The code compiled fine in Swift 2, and up to Swift 3 that shipped with Xcode 8 beta 3. In beta 4 and 5, the error "type of expression is ambiguous without more context" is output for the expression $0.residence:
public enum Maybe<T> : ExpressibleByNilLiteral {
case none, some(T)
public init() { self = .none }
public init(_ s: T) { self = .some(s) }
public init(nilLiteral: ()) { self = .none }
func map<U>(_ f: (T) -> U) -> Maybe<U> {
switch self {
case .none : return .none
case .some(let x) : return .some(f(x))
}
}
}
func pure<A>(_ x: A) -> Maybe<A> {
return Maybe(x)
}
infix operator >>= { associativity left }
func >>= <A,B> (m: Maybe<A>, f: (A) -> Maybe<B>) -> Maybe<B> {
switch m {
case .none : return .none
case .some(let m) : return f(m)
}
}
struct Room { let length: Int, width: Int }
struct Residence { let rooms: [Room] }
struct Person { let name: String, residence: Maybe<Residence> }
func livingSpace(_ person: Maybe<Person>) -> Maybe<Int> {
return person >>= { $0.residence }
>>= { pure($0.rooms.map { $0.length * $0.width }.reduce(0, combine: +)) }
}