10 months ago
OP you may have meant to have linked directly to https://soundness.dev/abacist
Not a scala person, but I like the idea of being able to shift between unit/measurement systems. Lots of strange little edge cases. Eg, how does rounding work in imperial, can I get 3.1415926535 meters to the closest 1/64th of an inch?
10 months ago
ah that's strange - I thought I had linked correctly. And now it's too late to edit :-(
10 months ago
This seems similar to the 'ComplexAmount' system I used to use in PHP and JavaScript programs for representing measurements using mixed units. Basically just a map of unit code => quantity. And for extra exactness, quantity would be represented as a rational number.
Was useful for a client that let you place orders using a mixture of USD and CAD (the alternative being a lot of 'canada'/'canadian'/'cad' fields added willy-nilly everywhere a cost needed to be represented; I don't know how people can stand to program that way). But also for generating G-code for a CNC router [1], when sometimes you want to model in mm, and sometimes in inches, and keep all the numbers exact until the last possible moment.
10 months ago
PHP and JavaScript are dynamic. Here you'll be able to pass distances as feet or meters, but if you try to pass in pounds you'll get a compile time error -- can't do that in dynamic languages :)
10 months ago
So, when I said JavaScript, I really meant TypeScript, and I found its gradual/structural typing system to be the most ergonomic type system I've ever used (if you want nominal types, it's pretty trivial to get there just by adding a compile-time-only tag, like `{ typeName?: "FooType" }`).
In this case, the TypeScript approach might be something like
const distanceInMm : {"mm": Rational} = toMm(distanceInArbitraryUnits);
I think I like Scala conceptually--when people talk about it I think "yeah, good idea!"--but every time I've looked at Scala code it struck me as having an excessive amount of boilerplate to wrap/unwrap stuff just to make the type checker happy.
The other bad-tasting thing about Scala is that I wrote a program[2] in it many years ago and then later came back to try to fix some bugs and the language had changed so much that I had to find some old version of it + an old JVM and Dockerize it. Docker's a godsend for this sort of thing, but kind of inconvenient for development.
[1] My notes about this approach in TypeScript: https://www.nuke24.net/plog/32.html
10 months ago
compare ⊤ and ⊥ in APL (a programming language old enough that the pound was not decimal, but still divided into shillings and pence, at its creation):