Fn2<Integer,Integer,Integer> add = (a, b)->a+b;

Fn1<Integer,Integer> add1 = add.apply(1);

Reader<Integer, String> reader = add1.reader()
                                     .map(i -> "hello " + i);

reader.apply(10);
//hello 11

Reader<Integer, String> r = reader.flatMap(i -> a -> a + i);
r.apply(10);
//10hello 11