I remember a long, long time ago, working on a project that handled lots of different types of physical quantities: distance, speed, temperature, pressure, area, volume, and so on. But they were all just passed around as "float" so you'd every so often run into bugs where a distance was passed where a speed was expected, and it would compile fine but have subtle or obvious runtime defects. Or the API required speed in km/h, but you passed it miles/h, with the same result. I always wanted to harden it up with distinct types so we could catch these problems during development rather than testing, but I was a junior guy and could never articulate it well and justify the engineering effort, and nobody wanted to go through the effort of explicitly converting to/from primitive types to operate on the numbers.

See https://learn.microsoft.com/en-us/dotnet/fsharp/language-ref...

this was very much my intent with https://raku.land/zef:librasteve/Physics::Measure

I had kind of written off using types because of the complexity of physical units, so I will be having a look at that!

My biggest problem has been people not specifying their units. On our own code end I'm constantly getting people to suffix variables with the units. But there's still data from clients, standard library functions, etc. where the units aren't specified!