[opminion]

If you see units as multiplicative factors:

1.5 USD = 1.5 * USD

65 mph = 65 * mile / hour

you can then use simple algebra to solve unit conversion and many other common deductive reasoning questions ("how many miles per gallon...?"), relying on the units to guide you to the solution.

There's probably a name for this, and it is indeed built into the SI notation (km/h vs mph).

[mckinney]

This is already implemented with manifold's unit expressions, but is made richer and more readable via concatenative features. For instance, '1.5 * USD' is not as readable as simply '1.5 USD'. However, unit expressions leverage operators for dimensional arithmetic:

Force f = 5 kg * 9.807 m/s/s; // result: 49.035 Newtons

Area space = (20ft + 2in) * (37ft + 7.5in); // result: 758 37/48 ft²

All unit expressions internally store amounts as SI units, which enables interunit expressions.

Length height = 6 ft + 4 cm; // mix SI and US units

out.println(height.to(ft)); // display any unit

You aren't limited to units. Generally, any concatenative sequence can be implemented. Like ranges:

IntegerRange range = 1 to 5;

Here the `to` identifier's type implements reactions to Number types to produce range types, which enables:

for (int i: 1 to 5) { out.println(i); }

See the manifold project's Unit and Science modules:

Units: https://github.com/manifold-systems/manifold/tree/master/man...

Science: https://github.com/manifold-systems/manifold/tree/master/man...

[chriswarbo]

Sounds like https://en.wikipedia.org/wiki/Dimensional_analysis