Loops

Lynxer has five loop keywords: while, for, doWhile, iterate and forever. Every one takes parentheses; forever and the condition-less doWhile are written forever(){ ... } and doWhile(){ ... }.

while

while (n > 0) {
    n -= 1;
}

for

for has two forms: the C style and the range style.

C style

for (int i = 0; i < 3; i = i + 1) {
    println(i);
}

for (int i = 0; i < 3) {   // update omitted: the increment is implicit
    println(i);
}

i++ and i-- do not exist — use i = i + 1, i += 1, or the implicit update.

Range style

The range form iterates an integer variable over a range of values:

for (int i = 0..=10..2) { ... }   // 0, 2, 4, 6, 8, 10
for (int i = 0..10..2) { ... }    // 0, 2, 4, 6, 8
for (int i = 1..=3..1) { ... }    // 1, 2, 3
for (int i = 1..=3) { ... }       // 1, 2, 3 — the step defaults to 1
for (int i = 10..=0..-2) { ... }  // 10, 8, 6, 4, 2, 0

The header is for (<type> <name> = <start> (.. | ..=) <end> [.. <step>]):

• ..= includes the end value; .. excludes it.
• The optional third value is the step. It must be non-zero; a negative step counts down, and the bound comparison flips accordingly. Step of 1 must be written explicitly when a third value is present (0..=10..1).
• Bounds and step are evaluated once and must be integers; a non-integer bound or a zero step is a source-located error.
• The loop variable is (re)declared and assigned each iteration, so the body sees it. Reassigning it inside the body does not change the iteration — the range is fixed.
• The C style and the range style cannot be mixed; the range style has no separate condition or update clause.

break and continue work as in any loop.

lynxer/examples/range_for.lynx pins all of these.

doWhile

doWhile (n < 3) {          // tests before each pass after the first
    n += 1;
}

doWhile(){                 // no-condition form: loops until `break`
    n += 1;
    if (n > 9) { break; }
}

iterate

iterate (4) {              // exactly four iterations
    println("tick");
}

iterate(count) requires an integer count.

forever

forever(){                 // loops until `break`
    if (done) { break; }
}

forever() without a reachable break prints a warning unless suppressForeverWarning() was called in setup().

break, continue, restart

• break leaves the innermost loop (and ends a switch).
• continue jumps to the next iteration.
• restart re-runs the current iteration from the top.

See also

• conditionals — if/elif/else and switch/case/default.
• language — the rest of the language reference.