Pitch: support for case and let when using where within switch and catch

[kyle-neerimcoding]

Thank you for clarifying. There could be some confusion where , preceding case means ‘or‘ and , following case means ‘and‘, but there is already strange behaviour without this change:

Ability to match a condition to multiple associated values from merged switch cases

I just had a small issue with a switch statement where I for some reason assumed that the where clause was already applied to every associated value of a merged switch case. enum Permission { case notSupported(UInt8) case readOnly(UInt8) case readWrite } let permission = Permission.notSupported(0) switch permission { case .notSupported(let code), .readOnly(let code) where code > 0: /* create the right error value */ default: /* create the default error value */ } The above exa…

"where" on a switch case with multiple items is misleading

I pitched a potential solution for this problem:

The compiler itself provides a warning when , as ‘or‘ is combined with where. Making another suggestion, this could be used for where to avoid the confusion:

switch a {
case {.one,.two} where ... :
// either one or two, but always check the where condition
case .one,
    .two where ... :
// one or (two with the where condition)
}

The choice of { } is to avoid looking like a tuple ( ) or like an array [ ]. Consistency with bound variables still applies.

Again, I am aiming to bring parity to where, if, guard and while, that is, make them act in the same way. If the , was ‘or‘ for where and simultaneously ‘and‘ for if, guard and while, this would contravene this aim.