On 25/10/15 6:45 PM, Nerve wrote:
On Sunday, 25 October 2015 at 05:05:47 UTC, Rikki Cattermole wrote:
Since I have no idea what the difference between Some(_), None and
default. I'll assume it's already doable.
_ represents all existing values not matched. In this case, Some(_)
represents any integer value that is not 7. None specifically matches
the case where no value has been returned. We are, in most languages,
also able to unwrap the value:
match x {
Some(7) => "Lucky number 7!",
Some(n) => "Not a lucky number: " ~ n,
None => "No value found"
}
Or something to that effect. The equivalent switch statement right now
would be:
if (x.hasValue()) {
switch (*x.peek!(int)) {
case 7: writeln("Lucky number seven!"); break;
default: writeln("Not a lucky number: ", *x.peek!(int)); break;
}
} else {
writeln("No value.");
}
I'm pretty sure e.g. opEquals/opCmp should work here.
Shouldn't need to switch upon a primitive type. Theoretically could do
it on a e.g. struct. Which has the special comparison that you want.
This does not return a value (is a procedural structure); the switch
cannot match null; in order to unwrap, we must call peek() again; and
between the extra if-else and the break statements, this is not as clean.
As a note, pattern matching could almost be considered an extended form
of the ?: operator, which matches over value cases rather than boolean
truthiness.
Apologies if this is all below you, I'm not in Andrei's or Walter's
league, just an interested party trying to make suggestions to better
the language.
No no it's fine. Only this morning I was toying with the idea of
variable length struct's on IRC. Turns out, wouldn't really work.
