Statements

Statements largely work like in C, but with some additions.

Expression blocks

Expression blocks (delimited using {| |}) are compound statements that opens their own function scope. Jumps cannot be done into or out of a function block, and return exits the block, rather than the function as a whole.

The function below prints World!

fn void test()
{
    int a = 0;
    {|
        if (!a) return;
        io::printf("Hello ");
        return;
    |};
    io::printf("World!\n");
}

Expression blocks may also return values:

fn void test(int x)
{
    int a = {|
        if (x > 0) return x * 2;
        if (x == 0) return 100;
        return -x;
    |};
    io::printfn("The result was %d", a);
}

Labelled break and continue

Labelled break and continue lets you break out of an outer scope. Labels can be put on if, switch, while and do statements.

fn void test(int i)
{
    if FOO: (i > 0)
    {
        while (1)
        {
            io::printfn("%d", i);
            // Break out of the top if statement.
            if (i++ > 10) break FOO;
        }
    }
}

Do-without-while

Do-while statements can skip the ending while. In that case it acts as if the while was while(0):

do
{
    io::printn("FOO");
} while (0);

// Equivalent to the above.
do
{
    io::printn("FOO");
};

Nextcase and labelled nextcase

The nextcase statement is used in switch and if-catch to jump to the next statement:

switch (i)
{
    case 1:
        doSomething();
        nextcase; // Jumps to case 2
    case 2:
        doSomethingElse();
}

It’s also possible to use nextcase with an expression, to jump to an arbitrary case:

switch (i)
{
    case 1:
        doSomething();
        nextcase 3; // Jump to case 3
    case 2:
        doSomethingElse();
    case 3:
        nextcase rand(); // Jump to random case
    default:
        io::printn("Ended");
}

Which can be used as structured goto when creating state machines.

Switch cases with runtime evaluation

It’s possible to use switch as an enhanced if-else chain:

switch (true)
{
    case x < 0:
        xless();
    case x > 0:
        xgreater();
    default:
        xequals();
}

The above would be equivalent to writing:

if (c < 0)
{
    xless();
}
else if (x > 0)
{
    xgreater();
}
else
{
    xequals();
}

Note that because of this, the first match is always picked. Consider:

switch (true)
{
    case x > 0:
        foo();
    case x > 2:
        bar();
}

Because of the evaluation order, only foo() will be invoked for x > 0, even when x is greater than 2.

It’s also possible to omit the conditional after switch. In that case it is implicitly assumed to be same as writing (true)

switch
{
    case foo() > 0:
        bar();
    case test() == 1:
        baz();
}