A Map is a collection that maps keys to values. Hash maps require keys that correctly support GetHashCode and Equals. Hash maps provide fast access (log32N hops). Count is O(1).
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// Create an empty PersistentHashMap and add some elements
PersistentHashMap<int,string> map =
PersistentHashMap<int, string>.Empty()
.Add(42,"hello")
.Add(99, "world");
Console.WriteLine(map[42]); // hello
Console.WriteLine(map[99]); // world
// Check no. of elements in the PersistentHashMap
Console.WriteLine(map.Length); // 2
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PersistentHashMaps are immutable and therefor allow to create new version without destruction of the old ones.
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PersistentHashMap<int, string> map2 =
map
.Add(104, "!")
.Add(42, "hi"); // replace existing value
Console.WriteLine(map2[42]); // hi
Console.WriteLine(map[42]); // hello
Console.WriteLine(map.Length); // 2
Console.WriteLine(map2.Length); // 3
// remove the last element from a PersistentHashMap
PersistentHashMap<int, string> map3 = map2.Remove(104);
Console.WriteLine(map3.Length); // 2
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