Design is the thing the client sees, implementation is the stuff they don't see. In this case the user is the one using match expressions. And they're seeing variables mutate inconsistently. It's practically impossible for a user not to see this, even if they wanted to. Calling that an implementation detail is like calling your car's steering wheel an implementation detail.
But I mean, you can call it that if you prefer. It's just as terrible and inexcusable regardless of its name. And yes, as I mentioned, I would have loved to have a good pattern matching system, but so far the "direction" they're going is actively damaging the language by introducing more pitfalls instead of fixing the existing ones (scopes, declarations, etc.). Just because pattern matching in the abstract could be a feature, that doesn't mean they're going in a good direction by implementing it in a broken way.
I guess like they say, the road to hell is paved with good intentions.
> Design is the thing the client sees, implementation is the stuff they don't see.
By this definition, bugs and other unintended consequences that the user encounters are "Design".
> Calling that an implementation detail is like calling your car's steering wheel an implementation detail.
Yes, if there weren't so many important decisions behind the outcome of a car being steered with a steering wheel, it could be a steering handle, or a steering joystick, or just about anything else that allows you to orient the front wheels of the car. The same is true of the pedals on the floor. Those could be implemented as controls on the steering wheel instead. Whether it's an implementation detail depends on the specificity of the feature in question. When I asked you about an "implementation detail", it was scoped to "the feature is pattern matching" (can I steer the car?) and you scoped it to "the feature is pattern matching without overwriting variables conditionally in surprising ways" (can I steer the car with failure modes that aren't fatal?).
Yes, I am definitely now quibbling over terms. I'm not sure what an appropriate response would have been? Just silence? You responded rather uncharitably and I didn't like it. I felt the need to defend my position.
Not silence, just continuing whatever your underlying point was if your goal wasn't to quibble over semantics. Now I have no idea what you're referring to, but this is clearly getting personal, so let's just leave this here. I think at this point we're both clear on the concrete problems with these features and what our positions are.
But I mean, you can call it that if you prefer. It's just as terrible and inexcusable regardless of its name. And yes, as I mentioned, I would have loved to have a good pattern matching system, but so far the "direction" they're going is actively damaging the language by introducing more pitfalls instead of fixing the existing ones (scopes, declarations, etc.). Just because pattern matching in the abstract could be a feature, that doesn't mean they're going in a good direction by implementing it in a broken way.
I guess like they say, the road to hell is paved with good intentions.