Problem Statement

Define two associative arrays, where one represents the following "base" data: And the other represents "update" data: Merge these into a new associative array that contains every key found in either of the source ones. Each key should map to the value in the second (update) table if that exists, or else to the value in the first (base) table. If possible, do this in a way that does not mutate the original two associative arrays. Obviously this should be done in a way that would work for any data, not just the specific data given here, but in this example the result should be:

Let's start with the solution:

var mergeMaps = Fn.new { |m1, m2|
    var m3 = {}
    for (key in m1.keys) m3[key] = m1[key]
    for (key in m2.keys) m3[key] = m2[key]
    return m3
}     

var base = { "name": "Rocket Skates" , "price": 12.75, "color": "yellow" }
var update = { "price": 15.25, "color": "red", "year": 1974 }
var merged = mergeMaps.call(base, update)
System.print(merged)