While i agree with the general idea, i disagree with the fact that the
compiler should handle the null and total cases, it can not handle the
total case, it has to be handled by the by the runtime, not the compiler.
I will use '?' for the total type, by example this switch is "total
enough"
sealed interface Stuff permits Pixel, Car {}
record Pixel(int x, int y, Color color) implements Stuff {}
record Car(Color color) implements Stuff {}
switch(stuff) {
case Pixel(? x, ? y, Color color) -> color;
case Car(Color color) -> color
}
We have agreed during one of our first meetings that we want that if
Pixel is changed to record Pixel(BigInteger x, BigInteger y, Color
color) {} with or without recompilation of the switch it should be Ok.
I don't recall agreeing to anything like this, so perhaps you can dig up
a reference, and I can try to reconstruct what I thought I was agreeing to?
It seems that you are arguing that the use site of a pattern match
should be unaffected by (possibly incompatible) changes in the
declaration of the pattern. But this can't possibly be what you are
suggesting.
(If you want to have a conversation on what declaration changes are
behaviorally compatible, that is a fine conversation!)
That doesn't mean that '?' can not be spelt 'var', but it demonstrates
that the corner cases should be managed by the runtime, not the compiler.
I don't understand what you mean by this distinction. The compiler
identifies the corner cases, and generates runtime code to handle them,
just like it does with expression enum switches today.
