Control flow

if

The if statement is pretty much what you would expect.

// The usual
if (someCondition) {
    // ...
} else if (anotherCondition) {
    // ...
} else {
    // ...
}

You can unwrap an optional with the -> operator.

if (opt -> unwrapped) {
    std\print(unwrapped);
}

You can downcast a value with the as operator.

final anything: any = "hello";

|...

if (anything as something: str) {
    std\print(something);
}

if can also be inlined and act as an expression. However this expression does not support null unwrapping or downcasting (those are available in expression using ?? and as?);

final value = if (something > 0) 12 else 13;

while and do .. until

Repeat a block of statements while or until a condition is true.

var i = 0;
while (i < 10) {
    i = i + 1;
}

var j = 10;
do {
    j = j - 1;
} until (j == 0)

for

for is pretty much the same statement as in C.

for (i: int = 0; i < 10; i = i + 1) {
    // ...
    break;
}

foreach

foreach can iterate over most data structures. The key/index variable can be omitted.

foreach (case in SomeEnum) {
    // ...
}

foreach (i, value in listOfStrings) {
    // ...
}

foreach (key, value in aMap) {
    // ...
}

foreach (i, char in aString) {
    // ...
}

final fibonnaciFib = &fibonnaci(10);
foreach (value in fibonnaciFib) {
    // ...
}

// The key can be omitted
foreach (char in aString) {
    // ...
}

foreach (i in 0..n) {
    // ...
}

break and continue

break will stop a loop.

while (true) {
    if (condition) {
        break;
    }
}

continue will skip any following statement and start the loop again.

while (true) {
    if (condition) {
        continue;
    }

    std\print("not reached if `condition` is true");
}

You can add a label to any loop and break/continue to it. This is useful when you have nested loops and want to break to an upper scope:

while (true) :here {
    if (condition) {
        break here;
    }

    std\print("not reached if `condition` is true");
}

Block expression

Block expression are lexical blocks that produce a value:

var value = from {
    // Doing some work here...

    out result;
}

out must appear once at the end of the block.