Comment by wavemode
5 hours ago
There's nothing preventing this for floats and ints in principle. e.g. the machine representation could be float, but the type in the eyes of the compiler could be `float | nan` until you check it for nan (at which point it becomes `float`). Then any operation which can return nan would return `float | nan` instead.
tbh this system (assuming it works that way) would be more strict at compile-time than the vast majority of languages.
This is a bit confused. You're saying `float`, but a float comes with NaN by default. Any float can take NaN values.
If you actually want the compiler to check this on the level of the type system, it'd have to be `NonNaNFloat | NaN`. Then you can check which one you have and continue with a float that is guaranteed to not be NaN.
But (importantly) a NonNaNFloat is not the same as a float, and this distinction has to be encoded in the type system if you want to take this approach seriously. This distinction is NOT supported by most type systems (including Rust's std afaik, fwiw). It's similar to Rust's NonZero family of types.