It should be possible to declare a function that returns only nil, and have its
return type be substitutable for any function that returns and Optional. This
is something like having a bottom type but not really. What I mean is:
func returnsNil(errCode:Int) -> nil {
logError(errCode) // A side-effect. Not FP, sosumi.
return nil
}
func returnAOptional() -> A? {
// Bla bla. We discover an error so we decide to bail and return nil.
return returnsNil(errCode) // Would be legal.
}
func returnsBOptional() -> B? {
// Bla bla. We discover an error so we decide to bail and return nil.
return returnsNil(errCode) // Would also be legal.
}
I seek a return type that conforms to any Optional -- I think that implies it
*must* (or correct me here) be nil.
Now perhaps this is already possible with wizardry from the Next Level. (There
always is one.)
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