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<p dir="auto">Hi Robert,</p>
<p dir="auto">When the conditional conformance feature arrives in Swift, it will allow us to express <code style="background-color:#F7F7F7; border-radius:3px; margin:0; padding:0 0.4em" bgcolor="#F7F7F7">extension Array : Encodable where Element : Encodable</code> and <code style="background-color:#F7F7F7; border-radius:3px; margin:0; padding:0 0.4em" bgcolor="#F7F7F7">extension Array : Decodable where Element : Decodable</code>.<br>
At the moment, this isn’t possible, so <code style="background-color:#F7F7F7; border-radius:3px; margin:0; padding:0 0.4em" bgcolor="#F7F7F7">Array</code> is unconditionally <code style="background-color:#F7F7F7; border-radius:3px; margin:0; padding:0 0.4em" bgcolor="#F7F7F7">Codable</code> and the failure happens at runtime. This will be a compile-time error in a future version of Swift.</p>
<p dir="auto">— Itai</p>
<p dir="auto">On 26 Oct 2017, at 9:47, Robert Nikander via swift-users wrote:</p>
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<p dir="auto">Hi,</p>
<p dir="auto">This error makes perfect sense, but I’m surprised it's a runtime error. I expected it at compile time. Am I doing something wrong? Is this on the type system to-do list?</p>
<p dir="auto">let c = JSONEncoder()<br>
struct Foo { … }<br>
let fs: [Foo] = [ Foo(...) ]<br>
let data = try! c.encode(fs) // Didn’t think this would compile</p>
<p dir="auto">The runtime error is: fatal error: Array<Foo> does not conform to Encodable because Foo does not conform to Encodable.</p>
<p dir="auto">Rob_______________________________________________<br>
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