Swift Array.filter() returning Iterable<> that can't be assigned to array

Elements Silver
1

Hi there, we are having this problem on Fire 8.3.91.1965 when compiling to java:

public class Foo
{
    let name: String
    
    public init(name: String)
    {
        self.name = name
    }
}

public class X
{
    static public func getFiltered(items: [Foo], name: String) -> [Foo]
    {
        // error E62: Type mismatch, cannot assign "Iterable<Foo>" to "swift.Array<Foo>"
        // appending .toSwiftArray() fixes in Fire but this but won't work in Xcode
        return items.filter { $0.name == name }
    }
}

print("Hi")

Since iteration works on Iterables you can work around it like this but it’s pretty clunky:

public class X
{
    static public func getFiltered(items: [Foo], name: String) -> [Foo]
    {
        let filtered = items.filter { $0.name == name }
        var x: [Foo] = []
        for f in filtered
        {
            x.append(f)
        }
        return x
    }
}

It’s a little odd how apple converts it straight to an array but there we go. What do you reckon?

2

Any thoughts on this one? In case it helps, here’s a sample project with the compilation error: FilterIssue.zip (326.7 KB)

3

As designed. We purposely return sequences, not arrays, consistently. The Apple Swift Base Library, honestly, looks like it was designed by someone who has no clue how to design a proper API, and no understanding of how concepts such as protocols work.

You can call .array (I believe — don’t have the code in front of me right now) to turn it into an array.

4

I discovered today that apple swift is actually is working a bit better here than you give it credit for.
Despite .filter() returning an array, and looking like its pretty non-functional, the return type is a LazyFilterCollection under the hood until its accessed.

Having to add .toSwiftArray causes us much grief in trying to write compatible code.