break

break exits the nearest enclosing loop.

Surface Syntax#

break;

Notes:

• break is a statement, terminated by a semicolon.
• break does not carry a value in the current language design; there is no break <expr> form.

Semantics#

When executed, break;:

• terminates the innermost enclosing loop (loop, while, or for), and
• continues execution at the statement immediately following that loop.

In nested loops, break only exits the nearest loop:

fn main () -> int {
  while true {
    while true {
      break; // exits the inner loop only
    }
    break; // exits the outer loop
  }
  return 0;
}

break does not exit the current function. Use return for that.

Type Checking Rules#

• break is only permitted inside a loop body.
• A break outside a loop is a type-check error (diagnostics, E2007).

Notes#

• break; is accepted inside loops (loop, while, and for) and lowered end-to-end.
• break; outside of a loop is rejected (E2007).

examples:

Common Pitfalls#

• Forgetting the semicolon (break is a statement).
• Expecting break to return a value (not supported).
• Using break outside a loop (rejected, E2007).