parameterizedMIDI.swift

infix operator >>= { }
func >>= <A, B> (x: A?, f: A -> B?) -> B? {
    if let val = x {
        return f(val)
    }
    return nil
}

protocol MIDIEnumerable {
    class func count() -> Int
    class func atIndex(Int) -> Self?
}

struct MIDI {
    
    static func enumerate<A: MIDIEnumerable>() -> GeneratorOf<A> {
        var index = 0
        return GeneratorOf<A> {
            return A.atIndex(++index)
        }
    }
    
    static func all<A: MIDIEnumerable>() -> [A] {
        var ret: [A] = []
        for val: A in enumerate() {
            ret.append(val)
        }
        return ret
    }
    
    class Object {
        let ref: MIDIObjectRef
        
        var properties: NSDictionary? {
            var cfProps: Unmanaged<CFPropertyList>?
            MIDIObjectGetProperties(ref, &cfProps, 1)
            
            return cfProps?.takeUnretainedValue() as? NSDictionary
        }
        
        init(ref: MIDIObjectRef) {
            self.ref = ref
        }
    }
    
    class Device: Object, MIDIEnumerable {
        class func count() -> Int {
            return Int(MIDIGetNumberOfDevices())
        }
        
        class func atIndex(index: Int) -> Self? {
            if index < count() {
                return self.init(ref: MIDIGetDevice(ItemCount(index)))
            }
            return nil
        }
    }
}