Comment by loeg
4 days ago
They named Result (or Expected) Optional? No, no, "optional" means "T or empty." Not "T or E."
https://c3-lang.org/language-fundamentals/functions/#functio...
4 days ago
They named Result (or Expected) Optional? No, no, "optional" means "T or empty." Not "T or E."
https://c3-lang.org/language-fundamentals/functions/#functio...
I think there is an important difference here from both Option<T> and Result<T, E>: the C3 optional doesn’t allow an arbitrary error type, it’s just a C-style integer error code. I think that makes a lot of sense and fits perfectly with their “evolution, not revolution” philosophy. And the fact that the syntax is ‘type?’ rather than ‘Optional<type>’ also eases any confusion.
Sure, there is a restriction on the type of E. This is similar to Zig's result ADT, I think?
I share your distaste for arbitrarily renaming concepts. However, I think if you only have one of the two in the language, Optional is the clearer name.
A result is already the informal name of the outcome or return value of every regular operation or function call, whereas an Optional is clearly not a regular thing.
I also think, from a pragmatic systems-design point of view, it might make sense to only support the Either/Result pattern. It's not too much boilerplate to add a `faultdef KeyNotInMap`, and then it's clear to the consumer why a real answer was not returned.
It's not just arbitrary renaming (Rust Result vs C++ Expected is fine) -- it's choosing a conflicting name for an extremely common abstract data type. If they wanted to call it "Elephant," great, but Optional is a well-known concept and Result/Expected isn't the same thing.
(I don't really object to the idea of skipping a real Optional<T> type in a language in favor of just Result<T, ()>.)
I would guess the two languages have little overlap in who they appeal to, and this is a bit closer to C semantics which is their north star. In C for functions that don’t return a value you often return a null for success or a return code that is a defined error code, which is exactly how Optional works in C3 (but you don’t write the word Optional in the function head). If you need to return a value in C you often pass an out param pointer and then still return either null or a defined error value. The improvement is you just write ‘type?’ for the return type to enable this and you don’t need an out param, but you still need the define (faultdef).
3 replies →
From what I can see there you never write the word “Optional” in your code. This is just what they named the feature which stays close to C semantics without the burden of *out params.
Oof.
You can name it "Result" or (questionably) "Either."
Not "Option," "Optional," or "Maybe;" those are something else.