Does anyone have an example of another programming language that

allows for addition of dictionaries/mappings?

kotlin does that (`to` means `:`) :

fun main() {
    var a = mutableMapOf<String,Int>("a" to 1, "b" to 2)
    var b = mutableMapOf<String,Int>("c" to 1, "b" to 3)
    println(a)
    println(b)
    println(a + b)
    println(b + a)
}

{a=1, b=2}
{c=1, b=3}
{a=1, b=3, c=1}
{c=1, b=2, a=1}