Control Flow

If and Else

⚠️ TODO

Example

if (x > 12) {
	if (x > 20)
		print("number is larger than 20");
} else {
	print("is smaller or equal to 12");
}

Unconditional Loop

An unconditional loop can be written with the loop keyword.

Example

loop {
	if (cond())
		break;
	print("looping...");
}

The following statements can be used to control the control flow of the loop:

• break;: Jumps out of the loop scope and continues execution at the statement following the loop
• continue: Jumps to the start of the loop scope, skipping the rest of the statements within the loop scope

In addition to these, return, throw and the ! operator can also cause the loop to be terminated.

C-Style For Loop

The first form of the for loop behaves very similar to C/C++ in terms of semantics and syntax. It consists of three optional parts, separated by semicolons:

1. The first part contains a list of declarations for variables that will be visible inside the loop scope.
2. The second part is a condition that must evaluate to true in order for the loop to keep iterating. Omitting it is equivalent to using true as the condition.
3. The third part is a list of expressions that will be evaluated after each loop iteration, including after using continue to force starting a new iteration.

Example

for (i: int = 0; i < 12; i++)
	print(i);

// the loop variable type can be inferred
for (i = 0; i < 12; i++)
	print(i);

// multiple variable declarations and increment
// expressions can be separated by commas
for (i = 0, j = 1; i * j < 12; i++, j++)
	print("$(i) × $(j) = $(i * j)");

// any part can be left off
var i = 0;
for (; i < 12;) {
	print(i);
	i++;
}

// equivalent to `loop {}`
var i = 0;
for (;;) {
	if (i >= 12)
		break;
	print(i);
	i++;
}

Range Based For Loop

The second for of the for loop operates on

Example

// loops over all integers from 0 to 9
for (i; 0 .. 10)
	print(i);

// loops over the integers 2, 5 and 8
for (n; [2, 5, 8])
	print(n);

// any input range can be iterated, a lazy
// range of even numbers from zero to 18 in
// this case
for (n; (0 .. 10).map(i => 2 * i))
	print(n);

// two loop variables can be declared, in
// which case the first variable will contain
// index of the loop iteration/range element
for (i, n; (0 .. 10).map(i => 2 * i))
	print("$(i+1). number: $(n)");

Switch Statement

Switch statements allow to branch code execution based on the value of an expression. Each case statement nested within the switch can match one or more possible values or ranges of values. Any value not matched by a case statement will be matched by the default statement.

A switch statement must handle all possible values of the input expression, either by explicitly matching all possible values, or by using a default statement. Each possible input value must match exactly one case or default statement.

⚠️ TODO

Example

switch (x) {
	case 0: print("zero");
	case 1: print("one");
	default: print("other");
}

enum E { a, b, c }
var e: E;
switch (e) {
	case E.a: print("A");
	case E.b: print("B");
	case E.c: print("C");
}