Control flow

If

An if statement has an if clause, followed by zero or more else if clauses, followed by an optional else clause.

var a: i32 = 2;
if a == 2 {
    a = a + 4;
else {
    a = a - 1;
}

Switch

A switch statement transfers control to one of a set of case clauses, or to the default clause, depending on the evaluation of a selector expression.

const c = 2;
var a : i32;
let x : i32 = generateValue();
switch x {
  case 0: {
    a = 1;
  }
  case 1, c { // Const-expression can be used in case selectors
    a = 3;
  }
  case 3, default { // The default keyword can be used with other clauses
    a = 4;
  }
}

Loop

A loop statement repeatedly executes a loop body. This repetition can be interrupted by a break or return statement. Optionally, the last statement in the loop body may be a continuing statement.

A continue statement transfers control in the nearest-enclosing loop: forward to the continuing statement at the end of the body of that loop, if it exists, otherwise backward to the first statement in the loop body, starting the next iteration.

var a: i32 = 2;
var i: i32 = 0;
loop {
  if i >= 4 {
    break;
  }

  let step: i32 = 1;
  i = i + step;
  if i % 2 == 0 {
    continue;
  }

  a = a * 2;
}

Loop with coninuing and break-if

var a: i32 = 2;
var i: i32 = 0;
loop {
  let step: i32 = 1;

  if i % 2 == 0 { continue; }

  a = a * 2;

  continuing {
    i = i + step;
    break if i >= 4;
  }
}

For

The for statement takes the form for (initializer; condition; update_part) { body } and is syntactic sugar on top of a loop statement with the same body.

for (var i: i32 = 0; i < 4; i++) {
  if a == 0 {
    continue;
  }
  a = a + 2;
}

While

The while statement is a kind of loop parameterized by a condition. At the start of each loop iteration, a boolean condition is evaluated. If the condition is false, the while loop ends execution. Otherwise, the rest of the iteration is executed.

var i: i32 = 0;
while (i < 5) {
    i++;
}