mckinney

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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...

Comment · 4 years ago

Ha! I implemented "concatenative" programming for Java as Binding [1] (or Unit) expressions, but had no idea. Seriously, never came across that term before this post.

The idea with binding expressions is the type of expression A and the type of expression B implement "reactions" with one another in order to form a binding expression when they are lexically adjacent.

65 mph

The type of `mph` defines a post reaction method with the type of `65` as an argument that results in type Rate. As I understand it this is concatenative, right?

Another example:

Money payment = 1.5M USD;

There are tons of these.

Concatenative programming in general feels like it should have a more prominent place in mainstream languages. Just my take.