zlacker

>>andsoi+(OP)
> "Modern" languages try to avoid exceptions by using sum types and pattern matching plus lots of sugar to make this bearable. I personally dislike both exceptions and its emulation via sum types. ... I personally prefer to make the error state part of the objects: Streams can be in an error state, floats can be NaN and integers should be low(int) if they are invalid.

Special values like NaN are half-assed sum types. The latter give you compiler guarantees.

>>esafak+uTb
Yeah, I'm not sure I've ever seen NaN called or as an example to be emulated before, rather than something people complain about.

>>saghm+pWc
Holy shit, I'd love to see NaN as a proper sum type. That's the way to do it. That would fix everything.

>>echelo+OZc
I suspect that this would result in a lot of .unwrap() calls or equivalent, and people would treat them as line noise and find them annoying.

An approach that I think would have most of the same correctness benefits as a proper sum type while being more ergonomic: Have two float types, one that can represent any float and one that can represent only finite floats. Floating-point operations return a finite float if all operands are of finite-float type, or an arbitrary float if any operand is of arbitrary-float type. If all operands are of finite-float type but the return value is infinity or NaN, the program panics or equivalent.

(A slightly more out-there extension of this idea: The finite-float type also can't represent negative zero. Any operation on finite-float-typed operands that would return negative zero returns positive zero instead. This means that finite floats obey the substitution property, and (as a minor added bonus) can be compared for equality by a simple bitwise comparison. It's possible that this idea is too weird, though, and there might be footguns in the case where you convert a finite float to an arbitrary one.)

>>amelia+DNd
> I suspect that this would result in a lot of .unwrap() calls or equivalent, and people would treat them as line noise and find them annoying.

I was thinking about this the other day for integer wrapping specifically, given that it's not checked in release mode for Rust (by default at least, I think there's a way to override that?). I suspect that it's also influenced by the fact that people kinda expect to be able to use operators for arithmetic, and it's not really clear how to deal with something like `a + b + c` in a way where each step has to be fallible; you could have errors propagate and then just have `(a + b + c)?`, but I'm not sure that would be immediately intuitive to people, or you could require it to be explicit at each step, e.g. `((a + b)? + c))?`, but that would be fairly verbose. The best I could come up with is to have a macro that does the first thing, which I imagine someone has probably already written before, where you could do something like `checked!(a + b + c)`, and then have it give a single result. I could almost imagine a language with more special syntax for things having a built-in operator for that, like wrapping it in double backticks or something rather than `checked!(...)`.