How to combine lists without using joins?

To merge two lists without using joins, you can simply concatenate them or add elements of one list to another. In Go, this is done using the append function.

Example of merging two slices:

list1 := []int{1, 2, 3}
list2 := []int{4, 5, 6}

combined := append(list1, list2...)
// combined now contains [1 2 3 4 5 6]

If you need to merge lists with removal of duplicates, you can use a map to track unique elements:

func mergeUnique(a, b []int) []int {
    m := make(map[int]bool)
    var result []int
    for _, v := range a {
        if !m[v] {
            m[v] = true
            result = append(result, v)
        }
    }
    for _, v := range b {
        if !m[v] {
            m[v] = true
            result = append(result, v)
        }
    }
    return result
}

Thus, merging lists without joins is simply adding elements and, if necessary, filtering for unique values.