while I like it, it doesn't actually seem that useful.... and given I work on IoT systems measuring all kinds of things in all kinds of units, it isn't at all useful for that. Kind of cool for when you are using F# as a calculator though
I haven't found them useful in my experience either, but they seem to have a real indispensable utility in some cases like algebra for simulations. At least, that is what I gathered from Matthew Crews who has the "FastFSharp" channel on YouTube and a Twitter account with the same name. (He employs mutability heavily for performance, so not what I think of as an average F# developer.)
