consider unifying value and type cases

[gavinking]

In an of clause we write stuff like of x | y | Type. Why can't we write that in a case?

Currently Ceylon forces you to distinguish type cases from value cases using the is keyword, which very occasionally pushes you towards nastiness like this:

case (is \Itrue | \Inull | Foo) { … }

Are there any really compelling reasons to not let you just write:

case (true | null | Foo) { … }

Historically, I think there were some reasons, since I had speculated about a lot of different kind of case conditions, case (satisfies ... ), etc, which we still don't have. Also the syntax for value cases was different to the syntax for union types with the ,s instead of |s.

Right now, I can't really think of much.

[luolong]

I think it might have been an artifact of treating case's as conditionals and thus making them closer in syntax with if statements.

Also, wasn't is Foo supposed to be doing some sort of type narrowing along the way?

[gavinking]

I think it might have been an artifact of treating case's as conditionals and thus making them closer in syntax with if statements.

Well, they're not defined as conditions in the spec.

Also, wasn't is Foo supposed to be doing some sort of type narrowing along the way?

Well, sure, that's what it does, of course, but now even value cases affect flow-sensitive typing (they narrow the else clause).