[A when Sequence?(A)]
overload getMreturn(#A) {
alias T = SequenceElementType(A);
return x -> A(x);
}

[S when Sequence?(S)]
overload mbind(x : S, f) = algorithms.concat(fmap(f, x));

var mreturn = getMreturn(#vectors.Vector[Int]);
main(){
    println(mbind(array(1,2,3), (x -> mbind(array(1,2,3), y -> mreturn(x*y)))));
}