What is a Map in Clojure?

Overview

A map is a collection that holds key-value pairs. The values stored in the map can be accessed using the corresponding key. In Clojure there are two types of maps:

1. Hash maps
2. Sorted maps

Hash maps

Hash maps are created using the hash-map function. Their keys support hashCode and equals. Let's see an example of a hash map:

Example

Explanation

Let's look at the explanation of the code above:

• Line 3: We define the function createMap.
• Line 4: We define a variable, exampleMap, and assign our map to it. The map is created using the hash-map function.
• Line 5: We use the println to print the created map (exampleMap).
• Line 6: We call the createMap function. This creates the hash map and prints its elements. Notice that the elements are printed in a random order.

Sorted maps

Sorted maps are created using the sorted-map function. The keys for a sorted map implement an instance of Comparable. The elements of the sorted map are sorted according to their keys. Let's take a look at an example of a sorted map:

Example

Explanation

Let's look at the explanation of the code above:

• Line 3: We define the function keyss.
• Line 4: We define a variable, exampleMap, and assign our map to it. We use the sorted-map method to create the map.
• Line 5: We add a statement to print the created map using the println method.
• Line 6: We call the createSortedMap function. This creates the sorted map and prints its elements. Notice that the elements are printed in a sorted order based on the keys.