switch expression
A switch expression allows the expression to take any of a number of results
depending which case matches a value. It is the expression analog of
a statement-level switch control structure.
Usage
String formatted = switch (val)
case (true) "yes"
case (false) "no"
case (is Float) formatFloat(val)
else val.string;
Description
When writing an expression it is often inconvenient to have
to "hoist" some simple conditional logic
into a number of statements using an switch control structure.
Compare the example in the Usage above with the equivalent using
a statement level switch:
String formatted;
switch(val)
case (true) {
formatted = "yes";
}
case (false) {
formatted = "no";
}
case (is Float) {
formatted = formatFloat(val);
}
else {
formatted = val.string;
}
switch expressions support type narrowing etc, just like the
switch statement. Likewise the else is required precisely when
the cases are not exhaustive.
Type
The type of a switch expression is the union type of the case expressions
and the else expression, if any.
