Clojure for Java developers: What you need to know

"The most remarkable thing you might notice when coming to Clojure from Java is that it is homoiconic, which means the code is written in the form of the language's data structures. This practice, also known as code as data, results in very consistent syntax with a limited number of keywords and constructs. It also creates a meta-programming model using "syntax-aware" code templates (called macros)."

"You will see this most frequently in the list syntax, because most of Clojure is written as lists. Here is a simple "Hello, InfoWorld" function in Clojure: (defn hello-infoworld [] (println "Hello, InfoWorld")) The parentheses indicate a list in Clojure. So, the definition of this function is essentially just the definition of a list with a keyword ( defn), a function name ( hello-infoworld), an empty argument vector ([]), and the function body."

Clojure combines Lisp's high-design heritage with modern practical capabilities and runs on the JVM with Java interoperability. Four key concepts define Clojure: code-as-data (homoiconicity), functional programming, immutability, and concurrency. Homoiconicity means code is represented using the language's own data structures, enabling macros and syntax-aware templates. Most Clojure code uses list syntax and vectors for data. Functions are defined as lists, with a defn keyword, name, argument vector, and body. Parentheses denote lists and the function body itself is a list containing calls and their arguments. Immutability and functional styles facilitate safer concurrent programming.

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