Crystal (programming language)
 |
|
| Paradigm | Multi-paradigm: Object-oriented |
|---|---|
| Designed by | Ary Borenszweig |
| Developer | Manas Technology Solutions |
| First appeared | June 18, 2014 |
| Preview release |
0.23.1 / July 13, 2017
|
| Typing discipline | static |
| Implementation language | Crystal |
| Platform | 'IA-32' (i386), 'x86-64' |
| OS | OS X, Linux, FreeBSD |
| License | Apache License 2.0 |
| Filename extensions | .cr |
| Website | crystal-lang |
| Influenced by | |
| Ruby,[1] C, Rust, Go,[1] C#,[1] Python[1] | |
Crystal is a general-purpose, object-oriented programming language designed and developed by Ary Borenszweig and Juan Wajnerman and more than two-hundred contributors.[2] Crystal is developed as open source software under the Apache License Version 2.0 with syntax inspired by Ruby. It is a compiled language with static type-checking but it is generally not required to specify the type of variables or method arguments. The types are resolved by an advanced global type inference algorithm.[3] The language is in an active development phase.
Contents
History[edit]
Work on the language began in June 2011,[4] with the purpose of creating a language which had the elegance and productivity of Ruby and the speed, efficiency and type safety of a compiled language.[5][4] Initially called Joy, it was quickly renamed to Crystal.[4]
In November 2013, the Crystal compiler (previously written in Ruby) became self-hosting.[6] The first official version was released in June 2014.[7] In July 2016 Crystal was added to the TIOBE Index.
Description[edit]
Although resembling the Ruby programming language in syntax, Crystal compiles to much more efficient native code using an LLVM backend, at the cost of disallowing the dynamic aspects of Ruby. However, the advanced global type inference used by the Crystal compiler, combined with the usage of union types, give Crystal the feel of a higher-level scripting language than many other comparable programming languages. The language has automated garbage collection and currently offers a Boehm collector. Crystal possesses a macro system and supports generics and method and operator overloading. Crystal's concurrency model is inspired by communicating sequential processes (CSP), and implements light-weight fibers and channels (for communicating between fibers) inspired by the Go programming language.[1]
Examples[edit]
Hello World[edit]
This is the simplest way to write the Hello World program in Crystal:
puts "Hello World!"
Or using an object-oriented programming style:
class Greeter
def initialize(@name : String)
end
def salute
puts "Hello #{@name}!"
end
end
g = Greeter.new("world")
g.salute
HTTP server[edit]
require "http/server"
server = HTTP::Server.new(8080) do |context|
context.response.content_type = "text/plain"
context.response.print "Hello world! The time is #{Time.now}"
end
puts "Listening on http://0.0.0.0:8080"
server.listen
Type inference and union types[edit]
The following code defines an array containing different types with no usable common ancestor. Crystal automatically creates a union type out of the types of the individual items.
desired_things = [:unicorns, "butterflies", 1_000_000]
p typeof(desired_things.first) # typeof returns the compile time type, here (Int32 | String | Symbol)
p desired_things.first.class # the class method returns the runtime type, here Symbol
Concurrency[edit]
Channels can be used to communicate between fibers, which are initiated using the 'spawn' keyword.
channel = Channel(Int32).new
spawn do
puts "Before first send"
channel.send(1)
puts "Before second send"
channel.send(2)
end
puts "Before first receive"
value = channel.receive
puts value # => 1
puts "Before second receive"
value = channel.receive
puts value # => 2
References[edit]
- ^ a b c d e Borenszweig, Ary. "Crystal 0.18.0 released!".
It's heavily inspired by Ruby, and other languages (like C#, Go and Python).
- ^ Contributers on git repository
- ^ Type inference part 1
- ^ a b c David, María Inti. "The story behind #CrystalLang".
- ^ Hsieh, Adler. "Why Crystal programming language?".
- ^ Borenszweig, Ary. "Good bye Ruby Thursday".
- ^ Borenszweig, Ary. "Crystal 0.1.0 released!".
