If statements

If statements have the usual form:

if some_bool_value {
    // ...
}

They may also bind an option value:

val some_opt: option[ref u8] = some "value"
if some_opt is some value {
    trust @print("Got value: {s}\n", {value})
}

In most cases, parentheses around the condition are optional. The same applies to for loop headers.

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For loops

A for loop without a header is an unconditional loop:

for {
    @puts("will print indefinitely.")
}

A for loop with a condition in its header behaves like a C-style while loop:

val x: mut i64 = 0
for x < 10 {
    x++
}

The C-style form consists of an initialization, a condition, and a post clause:

for i = 0, i < 10, i++ {
    trust @print("{d}\n", {i})
}

The three clauses are separated by commas. Semicolons are not part of the language grammar. The loop variable is declared implicitly, so no preceding val declaration is required.