Clojure:
Finding the length of a string

How to:

To get a string’s length in Clojure, use the count function:

(count "Hello, World!") ;=> 13

This means “Hello, World!” has 13 characters.

Deep Dive

The count function is the go-to in Clojure for finding the number of items in a collection, and strings are no exception since they can be treated as a sequence of characters. Historically, count has been part of Clojure since its early versions, reflecting its roots in Lisp where length operations are common on lists.

An alternative to count could be using Java interop because Clojure runs on the JVM:

(.length "Hello, World!") ;=> 13

This calls the .length method from Java’s String class. Though this alternative exists, using count is more idiomatic Clojure.

It’s worth mentioning that count is O(1) operation for strings, which means it takes a constant amount of time regardless of string length since the string’s length metadata is cached.

See Also

• Clojure official docs on count: https://clojure.github.io/clojure/clojure.core-api.html#clojure.core/count