3 ms·

> Money ask = 2.1M USD; Feels like it should be Money<USD> ask = 2.1M USD; Then methods like .plus() wouldn't even be defined for incompatible currencies.

• owlstuffing 2y ago
  Generally, the idea is that there is no incompatibility between units. Money is a bit exotic given its abstract nature wrt units / exchange rates. 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/manifold-deps-parent/manifold-science https://github.com/manifold-systems/manifold/tree/master/man... 2. https://github.com/manifold-systems/manifold/tree/master/manifold-deps-parent/manifold-ext#operator-overloading https://github.com/manifold-systems/manifold/tree/master/man...