Structured constants are not constants

[vtereshkov]

type S = struct {
    x, y, z: int
}

const (
    a = [2]int{2, 7}
    b = []real{3.14, 6.28}
    c = S{7, 8, -3}
)

fn main() {
    a[1] = 6
    b[0] = -0.666
    append(b, 17.2)
    c.x *= 2

    printf("%v  %v  %v\n", a, b, c)   // [2 6]  [-0.666 6.28 17.2]  {x: 14 y: 8 z: -3}
}

[vtereshkov]

Local structured constants are especially weird:

fn f(depth: int = 0) {

    const a = [2]int{5, 6}
    if a[1] > 10 {
        printf("OOPS!\n")  // OOPS!
    } 

    if depth < 5 {
        a[1]++
        f(depth + 1)
    }
}

fn main() {
    f()
}

[vtereshkov]

Without the concept of a pointer to constant (like const T * in C/C++), structured constants cannot be made truly constant and useful. Go disallows such constants, and so do we.