Control Flow
If Expressions
Noir supports if-else
statements. The syntax is most similar to Rust's where it is not required
for the statement's conditional to be surrounded by parentheses.
let a = 0;
let mut x: u32 = 0;
if a == 0 {
if a != 0 {
x = 6;
} else {
x = 2;
}
} else {
x = 5;
assert(x == 5);
}
assert(x == 2);
Loops
Noir has one kind of loop: the for
loop. for
loops allow you to repeat a block of code multiple
times.
The following block of code between the braces is run 10 times.
for i in 0..10 {
// do something
}
The index for loops is of type u64
.
Break and Continue
In unconstrained code, break
and continue
are also allowed in for
loops. These are only allowed
in unconstrained code since normal constrained code requires that Noir knows exactly how many iterations
a loop may have. break
and continue
can be used like so:
for i in 0 .. 10 {
println("Iteration start")
if i == 2 {
continue;
}
if i == 5 {
break;
}
println(i);
}
println("Loop end")
When used, break
will end the current loop early and jump to the statement after the for loop. In the example
above, the break
will stop the loop and jump to the println("Loop end")
.
continue
will stop the current iteration of the loop, and jump to the start of the next iteration. In the example
above, continue
will jump to println("Iteration start")
when used. Note that the loop continues as normal after this.
The iteration variable i
is still increased by one as normal when continue
is used.
break
and continue
cannot currently be used to jump out of more than a single loop at a time.