[anderskaseorg]

If it were true in the typical sense that “append() returns a new slice by value”, then you would expect to be able to mutate the old slice and the new slice independently from each other. But in reality, you can only do this if append() decided to reallocate, which only happens at some implementation-defined exponential pattern of sizes.

    package main
    
    import "fmt"
    
    func main() {
            a := []int{0}
            for i := 0; i < 40; i++ {
                    b := append(a, 0)
                    a[i] = 1
                    fmt.Printf("%d ", b[i])
                    a = b
            }
    }

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