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https://github.com/crystal-community/icr

Interactive console for Crystal programming language
https://github.com/crystal-community/icr

crystal repl

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Interactive console for Crystal programming language

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# ICR - Interactive Crystal [![Build Status](https://travis-ci.org/crystal-community/icr.svg?branch=master)](https://travis-ci.org/crystal-community/icr)



Interactive console for [Crystal Programming Language](http://crystal-lang.org/).



* [Usage](#usage)

  * [Require local files](#require-local-files)

* [Installation](#installation)

  * [Arch Linux](#arch-linux)

* [How does it work?](#how-does-it-work)

* [Commands and special locals](#commands-and-special-locals)

* [Update check](#update-check)

* [Development](#development)

* [Editor Integration](#editor-integration)

* [Contributors](#contributors)



## Usage



It's like irb, but for Crystal:



![GIF demo](https://raw.githubusercontent.com/crystal-community/icr/master/demo/demo.gif)



### Require local files

You can require local files by relative path (starts with `./`):

```

require "./src/my_cool_lib"

```



Libs can also be required from the cli:



```

$ icr -r colorize -r ./src/my_cool_lib

```



## Installation

Prerequisites:

* The latest version of crystal.

* Readline (for Debian/Ubuntu install `libreadline6-dev` package).

* LLVM development files.



Clone the repo:

```

git clone https://github.com/crystal-community/icr.git

```

Switch to repo-directory:

```

cd icr

```

Build:

```

make

```



Install:



```

sudo make install

```



### As a shard dependency



If you would like to include icr as a dependency, you can add it to your `shard.yml`



```yml

dependencies:

  icr:

    github: crystal-community/icr

    branch: master

```



Then just run `shards install` from your project!



Enjoy!



### Arch Linux



Arch Linux users can install ICR [from AUR](https://aur.archlinux.org/packages/crystal-icr/).



## How does it work?

* Every time you press `Enter` it adds a new instruction, generates a new crystal program, and executes it.

* The output is split into 2 parts: regular program output (e.g. output from `puts 10`) and the value returned by the last command.

* The regular output is saved, and when you type a new instruction, a new program is generated. The saved output is subtracted from the new output, and the difference is printed out. It creates an illusion that only new instructions are executed :)



## Commands and special locals



* `paste` - enables paste mode

* `debug` - toggles debug mode off and on. In debug mode icr will print the code before executing it

* `quit` or `exit` - exits current interactive console

* `reset` - clears out all of the accumulated commands

* `__` - holds the result of the last expression. Example:



```crystal

icr > "5" + "2"

=> "52"

icr > __.to_i - 10

=> 42



```



## Update check



ICR periodically checks for the new releases on Github. If your current version is out of date, it will simply show you a notice at start.



You can disable this behavior using `--disable-update-check` CLI flag.



## Development



To run tests:

```

make test

```



## Editor integration



 - [inf-crystal.el](https://github.com/brantou/inf-crystal.el) - Connects REPL buffer to the ICR subprocess in Emacs



## Contributors



- [greyblake](https://github.com/greyblake) Potapov Sergey - creator, maintainer

- [BlaXpirit](https://github.com/BlaXpirit) Oleh Prypin - fixes for Crystal 0.16

- [puppetpies](https://github.com/puppetpies) Brian Hood - support of records

- [jwoertink](https://github.com/jwoertink) Jeremy Woertink - support of -r option and number of other contributions

- [veelenga](https://github.com/veelenga) V. Elenhaupt - maintenance

- [MakeNowJust](https://github.com/MakeNowJust) TSUYUSATO Kitsune - syntax highlight support