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A read–eval–print loop (REPL) is also termed an interactive toplevel or a language shell.

Snippet from Wikipedia: Read–eval–print loop

A read–eval–print loop (REPL), also termed an interactive toplevel or language shell, is a simple interactive computer programming environment that takes single user inputs, executes them, and returns the result to the user; a program written in a REPL environment is executed piecewise. The term usually refers to programming interfaces similar to the classic Lisp machine interactive environment. Common examples include command-line shells and similar environments for programming languages, and the technique is very characteristic of scripting languages.

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A Read-Eval-Print Loop (REPL) is an interactive programming environment that takes single user inputs (reads), executes them (eval), and returns the result to the user (prints), then repeats the process (loop). REPLs are particularly useful for dynamic programming languages and are a staple in languages like Python, Ruby, and JavaScript. They provide a fast and efficient way to test code snippets, debug, and perform exploratory programming. By allowing immediate feedback, REPLs enhance the learning experience and productivity of developers by enabling rapid prototyping and iteration.

REPLs are integral to modern software development, especially in educational contexts and during the initial stages of coding projects. They help programmers quickly validate their code, understand new libraries, and experiment with new ideas without the need for a full-scale development environment setup. This immediate feedback loop fosters an iterative approach to problem-solving, making it easier to pinpoint and resolve errors. REPLs are also valuable for live coding sessions and presentations, where demonstrating concepts interactively can significantly enhance comprehension.

For more information, visit the [Wikipedia page on REPL](https://en.wikipedia.org/wiki/Read-eval-print_loop).

Many of the top 30 major programming languages offer a Read-Eval-Print Loop (REPL) for interactive use on Windows, MacOS, and Linux. Here is a list of those languages and their REPL availability:

1. **Python**: Available through the `python` command.

  - Installation: `python3` on most systems.
  - Example: `python3` or `python`.
  - [Source](https://docs.python.org/3/tutorial/interpreter.html)

2. **JavaScript**: Available through Node.js with the `node` command.

  - Installation: Node.js.
  - Example: `node`.
  - [Source](https://nodejs.org/en/)

3. **Ruby**: Available through the `irb` (Interactive Ruby) command.

  - Installation: Ruby.
  - Example: `irb`.
  - [Source](https://www.ruby-lang.org/en/documentation/quickstart/)

4. **Java**: Available through JShell since Java 9.

  - Installation: Java Development Kit (JDK).
  - Example: `jshell`.
  - [Source](https://docs.oracle.com/en/java/javase/11/tools/jshell.html)

5. **Go**: REPL available through third-party tools like `gore` and `yaegi`.

  - Installation: Gore or Yaegi.
  - Example: `gore` or `yaegi`.
  - [Gore](https://github.com/motemen/gore), [Yaegi](https://github.com/traefik/yaegi)

6. **Clojure**: Available through the `clojure` command.

  - Installation: Clojure.
  - Example: `clojure` or `lein repl`.
  - [Source](https://clojure.org/guides/repl/introduction)

7. **Scala**: Available through the `scala` command.

  - Installation: Scala.
  - Example: `scala`.
  - [Source](https://www.scala-lang.org/download/)

8. **Elixir**: Available through the `iex` (Interactive Elixir) command.

  - Installation: Elixir.
  - Example: `iex`.
  - [Source](https://elixir-lang.org/getting-started/introduction.html)

9. **Haskell**: Available through the `ghci` (GHC Interactive) command.

  - Installation: GHC.
  - Example: `ghci`.
  - [Source](https://www.haskell.org/ghci/)

10. **R**: Available through the `R` command.

   - Installation: R.
   - Example: `R`.
   - [Source](https://www.r-project.org/)

11. **Lisp**: Common Lisp available through `sbcl` (Steel Bank Common Lisp).

   - Installation: SBCL.
   - Example: `sbcl`.
   - [Source](http://www.sbcl.org/)

12. **Swift**: Available through the `swift` command.

   - Installation: Swift.
   - Example: `swift`.
   - [Source](https://swift.org/getting-started/)

13. **Julia**: Available through the `julia` command.

   - Installation: Julia.
   - Example: `julia`.
   - [Source](https://julialang.org/)

14. **Perl**: Available through the `perl` command with the `-d` flag.

   - Installation: Perl.
   - Example: `perl -d -e 0`.
   - [Source](https://www.perl.org/get.html)

15. **PHP**: Available through the `php` command with the `-a` flag.

   - Installation: PHP.
   - Example: `php -a`.
   - [Source](https://www.php.net/manual/en/features.commandline.interactive.php)

16. **Racket**: Available through the `racket` command or DrRacket IDE.

   - Installation: Racket.
   - Example: `racket` or DrRacket.
   - [Source](https://racket-lang.org/)

17. **Erlang**: Available through the `erl` command.

   - Installation: Erlang.
   - Example: `erl`.
   - [Source](https://www.erlang.org/downloads)

18. **Prolog**: Available through SWI-Prolog with the `swipl` command.

   - Installation: SWI-Prolog.
   - Example: `swipl`.
   - [Source](https://www.swi-prolog.org/)

19. **OCaml**: Available through the `ocaml` command.

   - Installation: OCaml.
   - Example: `ocaml`.
   - [Source](https://ocaml.org/)

20. **Scheme**: Available through Racket or other Scheme implementations like MIT/GNU Scheme.

   - Installation: Racket or MIT/GNU Scheme.
   - Example: `racket` or `mit-scheme`.
   - [Source](https://racket-lang.org/), [MIT/GNU Scheme](https://www.gnu.org/software/mit-scheme/)

21. **F#**: Available through the `fsharpi` command.

   - Installation: F#.
   - Example: `fsharpi`.
   - [Source](https://fsharp.org/)

22. **Groovy**: Available through the `groovysh` command.

   - Installation: Groovy.
   - Example: `groovysh`.
   - [Source](https://groovy-lang.org/)

23. **Kotlin**: Available through the `kotlinc` command with the `-script` option.

   - Installation: Kotlin.
   - Example: `kotlinc -script`.
   - [Source](https://kotlinlang.org/)

24. **Crystal**: Available through the `crystal play` command.

   - Installation: Crystal.
   - Example: `crystal play`.
   - [Source](https://crystal-lang.org/)

25. **Tcl**: Available through the `tclsh` command.

   - Installation: Tcl.
   - Example: `tclsh`.
   - [Source](https://www.tcl-lang.org/)

26. **Dart**: Available through the `dart` command with the `–enable-asserts` option.

   - Installation: Dart.
   - Example: `dart --enable-asserts`.
   - [Source](https://dart.dev/)

27. **ClojureScript**: Available through the `planck` REPL.

   - Installation: Planck.
   - Example: `planck`.
   - [Source](http://planck-repl.org/)

28. **Forth**: Various implementations like `gforth`.

   - Installation: Gforth.
   - Example: `gforth`.
   - [Source](https://www.gnu.org/software/gforth/)

29. **Nim**: Available through the `nim` command with the `-r` flag.

   - Installation: Nim.
   - Example: `nim -r`.
   - [Source](https://nim-lang.org/)

30. **Elixir**: Available through the `iex` command.

   - Installation: Elixir.
   - Example: `iex`.
   - [Source](https://elixir-lang.org/)

These REPLs are accessible on Windows, MacOS, and Linux, allowing developers to interactively test and debug their code. For more detailed information, you can refer to each language's official documentation.

REPL

A Read-Eval-Print Loop (REPL) is an interactive programming environment that facilitates the execution of code in a step-by-step manner. This environment reads user input, evaluates it, prints the result, and then loops back to wait for new input. REPLs are essential in many modern programming languages, providing immediate feedback and allowing developers to experiment and debug code more efficiently. They were popularized by early Lisp systems, where the REPL was an integral part of the development environment.

The concept of the REPL originated with Lisp, a programming language developed by John McCarthy in the late 1950s and early 1960s. Lisp's interactive environment was groundbreaking at the time, allowing programmers to write and test code snippets on the fly. The REPL became a defining feature of Lisp and influenced the design of many subsequent programming languages. Over the decades, REPLs have been adopted by various languages, each integrating this interactive feature to enhance the development process.

REPLs offer numerous benefits, making them indispensable tools in modern software development. One of the primary advantages is the immediate feedback loop, which allows developers to see the results of their code instantly. This helps in quickly identifying and fixing errors, understanding new libraries and APIs, and experimenting with different coding techniques. Additionally, REPLs are highly valuable in educational settings, where they aid in teaching programming concepts interactively.

In educational contexts, REPLs provide an excellent platform for interactive learning. Students can enter code snippets, see immediate results, and modify their code based on the feedback. This hands-on approach significantly enhances the learning process. Similarly, for prototyping, REPLs enable developers to test ideas quickly without the need for setting up a full project structure. This rapid iteration helps in refining concepts and accelerating the development cycle.

Python's REPL can be accessed simply by typing `python` or `python3` in the terminal. This opens an interactive shell where users can execute Python commands and see the results immediately.

```python

print(“Hello, World!”)

Hello, World!

2 + 2

4

def add(a, b):

… return a + b …

add(5, 3)

8 ```

JavaScript's REPL is available through Node.js. By typing `node` in the terminal, users can open an interactive shell to execute JavaScript code.

```javascript

console.log(“Hello, World!”)

Hello, World!

2 + 2

4

function add(a, b) {

… return a + b; … }

add(5, 3)

8 ```

Ruby's REPL, known as IRB (Interactive Ruby), allows for interactive coding. By typing `irb` in the terminal, users can enter the interactive Ruby shell.

```ruby irb(main):001:0> puts “Hello, World!” Hello, World! ⇒ nil irb(main):002:0> 2 + 2 ⇒ 4 irb(main):003:0> def add(a, b) irb(main):004:1> a + b irb(main):005:1> end ⇒ :add irb(main):006:0> add(5, 3) ⇒ 8 ```

One of the critical features of REPLs is their ability to handle errors gracefully. When an error occurs, the REPL typically prints an error message and returns to the prompt, allowing the user to correct their code and try again. This immediate feedback is crucial for learning and debugging.

```python

1 / 0

Traceback (most recent call last):

 File "", line 1, in 

Modern REPLs often include advanced features such as syntax highlighting, auto-completion, and history navigation. These features make the REPL more user-friendly and efficient. For example, IPython, an enhanced interactive Python shell, offers these capabilities and more, making it a powerful tool for scientific computing and data analysis.

Many integrated development environments (IDEs) and text editors offer built-in REPL support. This integration allows developers to write and test code within the same environment, improving workflow and productivity. For instance, Visual Studio Code and PyCharm provide integrated terminals where users can run REPL sessions.

Different programming languages have their own REPL implementations, tailored to their syntax and features. While the basic concept remains the same, the capabilities and user experience can vary significantly. For example, Haskell's GHCi and Scala's REPL offer powerful type inference and functional programming capabilities, which are intrinsic to these languages.

REPLs are particularly useful for exploratory programming, where developers experiment with code to explore new ideas and solutions. This iterative process of writing code, seeing the output, and refining the approach is facilitated by the REPL's immediate feedback loop.

REPLs are not only used for interactive programming but also for scripting and automation tasks. They can be embedded in scripts to execute code snippets dynamically, making them powerful tools for automating repetitive tasks and integrating different systems.

The popularity of REPLs has led to a vibrant community and ecosystem around them. Many languages have active communities that develop and maintain REPL tools, contribute plugins, and provide support through forums and documentation. This community support enhances the overall development experience.

In addition to standard REPLs, there are specialized educational tools that leverage REPL technology to teach programming concepts. Tools like Jupyter Notebooks, which use IPython, combine REPL functionality with rich text, graphics, and interactivity, making them ideal for teaching and learning.

The future of REPLs looks promising, with ongoing advancements in development environments and programming languages. Enhancements in user interfaces, integration with cloud services, and support for more languages are some of the areas where REPLs are expected to evolve. These advancements will continue to make REPLs indispensable tools for developers.

REPLs have revolutionized the way developers interact with programming languages, providing an interactive, immediate feedback loop that enhances productivity and learning. From their origins in Lisp to their widespread adoption in modern languages like Python, JavaScript, and Ruby, REPLs remain a crucial tool in the programmer's toolkit. By embracing REPLs, developers can write better code, learn more effectively, and innovate more rapidly.

For more information, visit the [Wikipedia page on REPL](https://en.wikipedia.org/wiki/Read-eval-print_loop).

Research:

• REPL on DuckDuckGo
• REPL on Google.com
• REPL on O'Reilly
• REPL on GitHub

• REPL on javatpoint.com
• REPL on w3schools.com
• REPL on tutorialspoint.com
• REPL on FreeCodeCamp.org

• REPL on AWS Docs
• REPL on Kubernetes.io
• REPL on docs.microsoft.com
• REPL on GCP Docs
• REPL on IBM Docs
• REPL on Red Hat Docs
• REPL on Oracle Docs

• REPL on YouTube
• REPL on Reddit
• REPL on scholar.google.com
• REPL on Stackoverflow
• REPL on Quora
• REPL on Dzone
• REPL on Hacker Noon
• REPL on InfoQ.com

• Android repl Function - repl on developer.android.com
• Angular repl Function - repl on angular.io
• Bash repl Function - repl on gnu.org/software/bash
• C repl Function - repl on iso-9899.info
• C Plus Plus repl Function | C++ repl Function - repl on cppreference.com
  • C Plus Plus repl Function | C++ repl Function - repl on isocpp.org
  • C Plus Plus repl Function | C++ repl Function - repl on cplusplus.com
• C Sharp repl Function | repl Function - repl on c-sharpcorner.com
• Clojure repl Function - repl on clojuredocs.org
• COBOL repl Function - repl on microfocus.com/documentation/visual-cobol
• Dart repl Function - repl on dart.dev
• IBM Db2 repl Function - Db2 repl on IBM.com
• Django repl Function - repl on docs.djangoproject.com
• Elixir repl Function - repl on elixir-lang.org
• Fortran repl Function - repl on fortran-lang.org
• Golang repl Function - Go repl Function - repl on golang.org
• Groovy repl Function - repl on docs.groovy-lang.org
• Haskell repl Function - repl on haskell.org
• Java repl Method - repl on javaspecialists.eu
  • Java repl Method - repl on baeldung.com
• JavaScript repl Function - repl on developer.mozilla.org
• Kotlin repl Method - repl on kotlinlang.org
• NumPy repl Function - repl on numpy.org
• Oracle PL/SQL repl Function - repl on docs.oracle.com
• Pandas repl Function - repl on pandas.pydata.org
• PHP repl Function - repl on php.net
• Python repl Function - repl on python.org
• PowerShell repl Function - repl on docs.microsoft.com
• R repl Function - repl on rdocumentation.org
• React repl Function - repl on reactjs.org
• REXX repl Function - repl on IBMmainframer.com
• Ruby repl Function - repl on ruby-lang.org
• Rails repl Function - repl on guides.rubyonrails.org
• Rust repl Function - repl on rust-lang.org
• Scala repl Function - repl on scala-lang.org
• Spring repl Function - repl on spring.io
• Swift repl Function - repl on swift.org
• T-SQL repl Function - repl on docs.microsoft.com
• TypeScript repl Function - repl on typescriptlang.org
• Vue.js repl Function - repl on vuejs.org

Research:

• repl on DuckDuckGo
• repl on O'Reilly
• repl on GitHub
• repl on Reddit
• repl on StackOverflow
• repl on YouTube

Fair Use Sources: