I have a struct that has to arrays. Each of those must have the
same sizes.
So while constructing the array, if you pass two arrays of
different sizes the constructor must return nothing.
In Rust I could easily use Option<T>. D has no answer to Optional
types as far as I am concerned. Is throwing exceptions the only
idiomatic way?
---
What I already considered:
* Using Nullable!T: Okay but Nullable!T has all the overloads for
regular T which makes the API even more unpredictable.
In Rust you don't just add a Some(44) and 34; No overloads for
Some<T> and i32 are allowed (purposefully).
* Option!T from the optional package: Has even worse problem IMO.
Not only it allows None + int but also it returns a `[]`. This
API is not to my liking. You could say well Haskell has fmap for
Optional etc, and I am aware of that, so does Rust with map etc.
But I am talking about basic things: like `+`.
* Value-based error handling like Go and C: well, that works but
the error checking is opt-in. There's no such thing as
[[nodiscard]] in D too so the user of the API might as well
forget to check for error value.
* if specialization: Clever workaround but sometimes the struct
may fail for complex reasons, not only for a single condition.
