Clojure:
Searching and replacing text

How to:

In Clojure, we wield the clojure.string/replace function to search and replace text. Let’s cut to the chase with some code:

(require '[clojure.string :as str])

;; Basic replacement
(str/replace "I like apples" "apples" "oranges")
;; => "I like oranges"

;; Using a regular expression to replace all vowels
(str/replace "Hello, World!" "[AEIOUaeiou]" "*")
;; => "H*ll*, W*rld!"

;; Replacement with a function for dynamic changes
(str/replace "I have 2 apples and 5 bananas"
             #"\d+"
             (fn [match] (str (inc (Integer/parseInt match)))))
;; => "I have 3 apples and 6 bananas"

Simple as that. Run it, and you’ll see the transformations right there in your REPL.

Deep Dive

Searching and replacing in text isn’t new. It’s age-old in computing. We got it from early editors like sed in Unix. We’ve come a long way since then.

Clojure, being on the JVM, means you’ve got Java’s regular expression prowess under the hood. Performance-wise, it’s nifty for quick scripts but remember, overuse in large-scale text processing can hurt performance.

As for alternatives, besides clojure.string/replace, there’s regex-based libraries or even writing your custom function if you’re feeling adventurous. Think about replace-first if you only need a one-shot change.

Functionally, Clojure’s approach to immutability means each replacement results in a new string. No mutable strings mean fewer bugs and surprises.

See Also

To dive deeper, check out these resources:

• Clojure’s clojure.string API documentation
• On regular expressions, Java’s Pattern class