Feels like it should be
Money<USD> ask = 2.1M USD;
For instance, physical dimensions store values as SI units, regardless of supplied unit, but retain the supplied unit type as a display hint.
Here, the Length dimension illustrates working with amounts of any unit.
Length orbit = 250 mi;
Length moon = 238000 km;
Length landing = moon + orbit;
display(landing); // prints 148,136.344 mi
display(landing.to(km)); // prints 238,402.336 km
// where
display(landing.to(mi) == landing.to(km)); // prints true
// perhaps a better example
Rate rate = 1.41 km/s;
Time duration = 76 hours;
Length distance = rate * duration;
// make your own unit constants
RateUnit kps = km/s;
rate = 1.41 kps;
You can play with the manifold-science[1] project, it implements the complete SI physical dimensions and many derived dimensions along with comprehensive operator overloading[2] support etc. to make working with and reading code using quantities more productive in Java.
1. https://github.com/manifold-systems/manifold/tree/master/man...
2. https://github.com/manifold-systems/manifold/tree/master/man...