YARR

YARR (Yet Another Ruby REPL) is a Ruby REPL (just a hobby, won't be big and professional like Pry). YARR was inspired by groovysh¹, IRB², Pry³, Bash ⁴ and Vim⁵.

Installation

Install the gem:

$ gem install yarr

Features

An interactive shell for evaluating Ruby code from the command-line. YARR is a command-line application which allows easy access to evaluate Ruby expressions, define classes and run simple experiments. It also features command history.

Evaluating Expressions

Simple Expressions

ruby:001> puts "Hello"
Hello
===> nil
ruby:002> [1,2,3].max
===> 3

Multi-line Expressions

Multi-line/complex expressions (like closure or class definitions) may be defined over several lines. When the shell detects that it has a complete expression it will evaluate it.

ruby:001> class Foo
ruby:001*   def bar
ruby:001*     lambda do
ruby:001*       1
ruby:001*     end
ruby:001*   end
ruby:001* end
===> :bar
ruby:002> Foo.new.bar.call
===> 1

Variables

Set a shell variable for later use.

ruby:001> foo = "bar"
===> bar

Functions

Functions can be defined in the shell, and will be saved for later use.

Defining a function is easy:

ruby:001> def hello(name)
ruby:001*   puts "Hello #{name}"
ruby:001* end
===> :hello

And then using it is as one might expect:

ruby:002> hello("Arturo")
Hello Arturo
===> nil

Variables and functions share the same namespace, be careful:

ruby:001> foo = 10
===> 10
ruby:002> def foo
ruby:002*   5
ruby:002* end
===> :foo
ruby:003> foo
===> 10

Commands

The shell has a number of different commands, which provide access to the shell’s environment.

:exit or :quit

Exit the shell.

This is the only way to exit the shell. No Ctrl-c, sorry.

ruby:001> :exit

:help

Display the list of commands (and aliases).

ruby:001> :help

Available commands:
  :exit    Exit the shell
  :help    Display this help message
  :hist    Display edit-line history
  :quit    Alias to :exit
  :number  Execute a specific expression from history
  :! cmd   Execute a shell command à la Vim

:hist

Display the shell history.

ruby:001> def foo
ruby:001*   "bar"
ruby:001* end
===> :foo
ruby:002> var = 10
===> 10
ruby:003> :! echo "Yay"
Yay
ruby:004> :hist
  001  def foo
         "bar"
       end
  002  var = 10
  003  :! echo "Yay"
  004  :hist

:number

Execute a specific expression from history, e.g. :1 or :001.

ruby:001> var = 10
===> 10
ruby:002> var = 5
===> 5
ruby:003> var = 8
===> 8
ruby:004> :2
===> 5

:! cmd

Execute a shell command à la Vim.

ruby:001> :! cal
   February 2015
Su Mo Tu We Th Fr Sa
 1  2  3  4  5  6  7
 8  9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28

Who made this?

This was made by Arturo Herrero under the MIT License. You can also find me on Twitter @ArturoHerrero.