Control Flow

if / else

if x > 0 {
    stdio.Println(1)
} else {
    stdio.Println(0)
}

Braces are required. There is no else if; an else branch that starts with another if must nest it in its own block:

if x % 15 == 0 {
    stdio.PrintlnStr("FizzBuzz")
} else {
    if x % 3 == 0 {
        stdio.PrintlnStr("Fizz")
    } else {
        stdio.Println(x)
    }
}

for

for covers every loop form. With a condition, it behaves like a while loop:

var i int = 0
for i < 10 {
    stdio.Println(i)
    i = i + 1
}

With no condition, it loops forever until a break:

for {
    if done() {
        break
    }
}

while and loop are accepted as aliases for for; the grammar is the same either way, condition or none. There is no C-style three-part for (init; cond; step) form and no for x in range.

break and continue

break exits the nearest enclosing loop. continue skips to the next iteration’s condition check. Both are rejected at type-check time outside a loop, and a break or continue written inside a closure body only sees loops in that closure’s own body, not loops in the function the closure is defined inside.

var found int = 0
var n int = 2
for found < 10 {
    if math.IsPrime(n) == 0 {
        n = n + 1
        continue
    }
    stdio.Println(n)
    found = found + 1
    n = n + 1
}

return

return with no value exits a function that returns nothing. return expr exits with a value; the function’s declared return type and expr’s type must be compatible. A function falling off the end of its body without an explicit return returns the return type’s zero value (or, for main, exits with status 0).