gistfile1.hx

abstract Choice<A,B>(Dynamic) {
  	inline function new (x:Dynamic) this = x;
	@:from static inline function fromA <A,B>(x:A):Choice<A,B> return new Choice(x);
	@:from static inline function fromB <A,B>(x:B):Choice<A,B> return new Choice(x);
}

class Test {

	public static function expectStringOrInt (x:Choice<String, Int>) {
		
	}
	public static function main () {
		expectStringOrInt(1); //works
		expectStringOrInt("hi"); //works
		expectStringOrInt({ a : "hi"}); //error
		expectStringOrInt(1.1); // error
	}
}