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Best Clojure Tutorial | Ultimate Guide to Learn [UPDATED]

Last updated on 10th Aug 2022, Blog, Tutorials

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The Clojure programing language

Clojure could be a dynamic, all-purpose programming language, combining the accessibility associated with degreed interactive development of a scripting language with an economical and strong infrastructure for multithreaded programming. Clojure could be a compiled language, nevertheless remains utterly dynamic – each feature supported by Clojure is supported at runtime. Clojure provides easy accessibility to the Java frameworks, with optional sort hints and sort logical thinking, to confirm that calls to Java will avoid reflection.

Clojure could be an accent of Lisp, and shares with Lisp the code-as-data philosophy and a strong macro system. Clojure is a useful programming language, and offers an upscale set of changeless, persistent knowledge structures. Once a mutable state is required, Clojure offers a software system transactional memory system and reactive Agent system that guarantee clean, correct, multithreaded styles. I hope you discover Clojure’s combination of elegant, powerful, sensible and fun to use. Rich Hickey Author of Clojure and CTO Cognitect.


Clojure includes a set of helpful options that are a straightforward, coherent, and powerful tool.

Dynamic Development

Clojure could be a dynamic atmosphere you’ll act with. the majority of the language constructs are unit reified, and therefore will be examined and adjusted. you’ll grow your program, with knowledge loaded, adding options, fixing bugs, testing, in associate degree unbroken stream.

Functional Programming

Functional Programming

Clojure provides the tools to avoid mutable state, provides functions as fantabulous objects, and emphasizes algorithmic iteration rather than side-effect primarily based iteration. Clojure is impure, nevertheless stands behind the philosophy that programs that area unit additional useful area unit additional strong.


Clojure could be a member of the Lisp family of languages. Several of the options of Lisp have created it into different languages, however Lisp’s approach to code-as-data and its macro system still set it apart. to boot, Clojure’s maps, sets, and vectors are unit as top quality in Clojure as lists are unit in Lisp.

Runtime Polymorphism

Systems that utilize runtime polymorphism are easier to alter and extend. Clojure offers straightforward, powerful and versatile mechanisms for runtime polymorphism. Clojure’s protocols and data types options add mechanisms for abstraction and arrangement definition with no compromises vs the facilities of the host platform.

Concurrent Programming

Clojure simplifies multi-threaded programming in many ways. as a result of the core knowledge structures being unit changeless, they will be shared pronto between threads. Clojure, being a sensible language, permits state to alter however provides mechanism to confirm that, once it will therefore, it remains consistent, whereas assuaging developers from having to avoid conflicts manually victimization locks etc.

Hosted on the JVM

Clojure is meant to be a hosted language, sharing the JVM sort system, GC, threads etc. All functions are unit compiled to JVM bytecode. Clojure could be a nice Java library shopper, providing the dot-target-member notation for calls to Java. Clojure supports the dynamic implementation of Java interfaces and categories. collection of older, thoughtful technologists, dependent on serving to organizations deploy technology effectively and humanely to create higher futures. In addition to operating directly with corporations to deliver innovative solutions, Cognitect offers beaux arts review, coaching and talent development services for corporations and groups deploying Clojure and ClojureScript.

Cognitect also are the manufacturers of Datomic, a transactional info with a versatile knowledge model, elastic scaling, and made queries. Datomic Ions allow you to develop Clojure applications for AWS by deploying your code to a running Datomic cluster. Clojure could be a high level, dynamic, useful programming language. It’s designed, supports the LISP programming language, and has compilers that creates it attainable to be run on each Java and .Net runtime atmosphere. This tutorial is fairly comprehensive and covers numerous functions concerned in Clojure. All the function area units explained victimization examples for simple understanding.


This tutorial is meant for all those software system professionals UN agency area units keen on learning the fundamentals of Clojure and the way to place it into observation.


Before continuing with this tutorial, familiarity with Java and LISP programming languages is most popular.

1. Introduction: Clojure could be a useful programming language that runs entirely on the Java Virtual Machine, similar thanks to Scala and Kotlin. Clojure is taken into account to be a Lisp spinoff and can be acquainted to anyone UN agency has expertise with different Lisp languages. This tutorial offers an associate degree introduction to the Clojure language, introducing the way to start with it and a few of the key ideas to however it works.

2. putting in Clojure: Clojure is offered as installers and convenience scripts to be used on the UNIX operating system and macOS. sadly, at this stage, Windows does not have such an associate degree installer.However, the UNIX operating system scripts would possibly add one thing like Cygwin or Windows Bash. There’s conjointly an internet service that may be accustomed to taking a look at the language, and older versions have a standalone version that may be used.

Standalone transfer

Standalone transfer

The standalone JAR file will be downloaded from wiz Central. sadly, versions newer than one.8.0 now do not work this fashion simply thanks to the JAR file having been split into smaller modules.

1.freestar:Once this JAR file is downloaded, we will use it as associate degree interactive REPL just by treating it as associate degree practicable JAR:

  • $ java -jar clojure-1.8.0.jar
  • Clojure 1.8.0
  • user=>

2. net Interface to REPL: A web interface to the Clojure REPL is offered at for the United States of America to undertake without having to transfer something. Currently, this solely supports Clojure one.8.0 and not the newer releases.

3. Installer on MacOS: If you employ macOS and have inebriant put in, then the newest unleash of Clojure will be put in easily.

4.$ brew install clojure: This will support the newest version of Clojure – one.10.0 at time of writing. Once put in, we will load the REPL just by victimization the clojure or clj commands:

  • $ clj
  • Clojure 1.10.0
  • user=>

Installer on UNIX operating system

A self-installing shell script is offered for United States of America to put in the tools on Linux:

  • freestar
  • $ curl -O
  • $ chmod +x
  • $ sudo ./
  • As with the macOS installer, these are offered for the foremost recent releases of Clojure and might be dead victimization of the clojure or clj commands.

1.easy sorts: Clojure is made on prime of the JVM, and per se we’ve got access to constant normal sorts as the other Java application. sorts square measure generally inferred mechanically and do not have to be specific expressly.

2.distinctive Collections: We’ve seen that the means we have a tendency to access assortment|a set|a group} varies counting on the sort of collection we’ve got. we’ve got a collection of functions we are able to use to work out this, each during a specific and a lot of generic manner.

  • user=> (conj [1 a pair of 3] 4) ; Adds to the top
  • [1 2 3 4]
  • user=> (conj ‘(1 a pair of 3) 4) ; Adds to the start
  • (4 1 2 3)
  • user=> (conj #{1 a pair of 3} 4) ; Unordered
  • #
  • user=> (conj #{1 a pair of 3} 3) ; Adding AN already gift entry will nothing
  • #
  • We can additionally take away entries from a collection exploitation disj. Note that this does not work on an inventory or vector, as a result of they’re strictly ordered:
  • user=> (disk #{1 a pair of 3} 2) ; Removes the entry
  • #
  • user=> (disk #{1 a pair of 3} 4) ; will nothing as a result of the entry wasn’t gift
  • #
  • Adding new components to a map is completed exploitation assoc. we are able to additionally take away entries from a map exploitation dissoc:
  • user=> (assoc one :b 2} :c 3) ; Adds a replacement key
  • user=> (assoc one :b 2} :b 3) ; Updates AN existing key
  • user=> (dissoc one :b 2} :b) ; Removes AN existing key
  • user=> (dissoc one :b 2} :c) ; will nothing as a result of the key wasn’t gift

3.useful Programming Constructs: Clojure is, at its heart, a useful programming language. This implies that we’ve got access to several ancient useful programming ideas – like map, filter, and reduce. These typically work constantly as in alternative languages. the precise syntax could also be slightly completely different, though.

Specifically, these operates typically take the function to use because the initial argument, and therefore the assortment to use it to because the second argument:

  • user=> (map INC [1 a pair of 3]) ; Increment each price within the vector
  • (2 3 4)
  • user=> (map INC #{1 a pair of 3}) ; Increment each price within the set
  • (2 4 3)
  • user=> (filter odd? [1 a pair of three four 5]) ; solely come odd values
  • (1 3 5)
  • user=> (remove odd? [1 a pair of three four 5]) ; solely come non-odd values
  • (2 4)
  • user=> (reduce + [1 a pair of three four 5]) ; Add all of the values along, returning the add
  • 15

Management Structures

As with all general purpose languages, Clojure options require normal management structures, like conditionals and loops.


Conditionals square measure handled by the if statement. This takes 3 parameters: a take a look at, a block to execute if the take a look at is true, and a block to execute if the take a look at is fake. every of those will be an easy price or a regular list which will be evaluated on demand:

  • user=> (if true one 2)
  • 1
  • user=> (if false one 2)
  • 2

Our take a look at will be something in any respect that we want – it does not have to be a true/false price. It may also be a block that gets evaluated to convey U.S. the worth that we have a tendency to need:

  • user=> (if (> one 2) “True” “False”)
  • “False”
  • All of the quality checks, together with =, >, and (if zero “True” “False”)
  • “True”
  • user=> (if [] “True” “False”)
  • “True”
  • user=> (if nix “True” “False”)
  • “False”


Our useful support on collections handles abundant process work – rather than writing a loop over the gathering, we have a tendency to U.S.e the quality functions and let the language do the iteration for us. Outside of this, the process is completed entirely using the exploitation formula. we are able to write algorithmic functions, or we are able to use the loop and recur keywords to write down a algorithmic vogue loop:

  • user=> (loop [accum [] i 0]
  • (if (= i 10)
  • accum
  • (recur (conj accum i) (inc i))
  • ))
  • [0 one a pair of three four five six seven eight 9]

The loop decision starts AN inner block that’s dead on each iteration and starts by fitting some initial parameters. The recur decision then calls into the loop, providing ensuing parameters to use for the iteration. If recur isn’t referred to as, then the loop finishes. In this case, we have a tendency to loop anytime that the i price isn’t up to ten, so as presently because it is up to ten, we have a tendency to instead come the accumulated vector of numbers.


This article has given AN introduction to the Clojure programming language and shows however the syntax works and a few of the items that you simply will do .

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