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.");
}
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.
