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:

main() {
	var base = {
		'name':   'Rocket Skates',
		'price':  12.75,
		'color':  'yellow'
	};

	var newData = {
		'price': 15.25,
		'color': 'red',
		'year':  1974
	};

	var updated = Map.from( base ) // create new Map from base
		..addAll( newData ); // use cascade operator to add all new data
	
	assert( base.toString()    == '{name: Rocket Skates, price: 12.75, color: yellow}' );
	assert( updated.toString() == '{name: Rocket Skates, price: 15.25, color: red, year: 1974}');


}