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We are delivering a new release with several bugfixes and improvements. Below we list the most important or interesting changes, without mentioning several bugfixes and smaller enhancements. For more details, visit the changelog. Breaking changes are marked with ⚠️. Pre-built packages are available on GitHub Releases and our official distribution channels. See crystal-lang.org/install for installa

We are delivering a new release with several bugfixes and improvements. Below we list the most important or interesting changes, without mentioning several bugfixes and smaller enhancements. For more details, visit the changelog. Breaking changes are marked with ⚠️. Pre-built packages are available on GitHub Releases and our official distribution channels. See crystal-lang.org/install for installa

Crystal's interpreter – A very special holiday present 29 Dec 2021 The awaited Crystal interpreter has been merged. To use it, you need to compile Crystal with a special flag and, at the time of writing, the official releases (.deb, .rpm, docker images, etc.) are not being compiled with it. This post doubles as a F.A.Q. for this special feature. Let’s start from the very beginning: Why Crystal nee

Ary Borenzweig Brian J. Cardiff Juan Wajnerman +450 more The release of the first major release of Crystal arrives after many years of hard work. With thousands of contributions from people worldwide, it was finally possible to find consensus for what truly mattered for 1.0 and what could wait for future releases. Getting here wasn’t an easy journey, filled with enriching, controversial, delightfu

Currently the main goal of the Crystal core team is to reach 1.0 in the near future. Since achieving that goal involves a number of non-obvious tradeoffs, we want to use this post to shed some light on those inherent tensions and how they drive our work and priorities for the next few releases. There are three main aspects of the Crystal ecosystem that in a way compete for resources and design dec

Crystal 0.26.0 has been released! This release is focused on polishing APIs, bug fixing the compiler, keep working on windows support and some intermediate language changes for future releases. There were 119 commits since 0.25.1 by 24 contributors. Language changes Revert: Do not collapse unions for sibling types In 0.25.0 we tried to improve the inferred type of unions of sibling types. Although

This guest post by Robert Carpenter will introduce you to Amber, a Rails/Phoenix-like web framework for Crystal. Don’t forget to reach out to us if you want to share some experience of your own. The Amber Framework is a young and growing web framework written in our favorite language, Crystal. It shares many similarities with Rails, but - like Crystal itself - compatibility with Rails is not a des

This is a guest post by Mark Siemers, who kindly volunteered to suggest a series of Crystal blog posts. Expect more to come, or - even better - contact us about writing your own post. 1. Extremely low learning curve Think of some languages that have become popular in the last 5-10 years. What comes to mind? Elixir, Go, Rust perhaps? They all have performance advantages over Ruby but are more diffi

This guest post is an interview that Ivo Balbaert had with Peter Schols from Diploid about their Crystal in Production story. This interview will also be part of the Programming Crystal book that Ivo is writting - and we can’t wait to read! We’d like to thank both of them for taking the time to share their experience, and to invite any other companies or individuals using Crystal in a production e

Concurrency¶ Concurrency vs. Parallelism¶ The definitions of "concurrency" and "parallelism" sometimes get mixed up, but they are not the same. A concurrent system is one that can be in charge of many tasks, although not necessarily executing them at the same time. You can think of yourself being in the kitchen cooking: you chop an onion, put it to fry, and while it's being fried you chop a tomato

This post is the first from our guest writers series. If you have built something awesome using Crystal and want to share your experience here on the blog, let us know! Today’s guest author is Leonard Schütz. He created the Charly programming language as a means to learn how to create a programming language, and after a first iteration in Ruby, he moved to Crystal to implement the language interpr

Crystal has gone a long way since we started it over five years ago. What was once an experiment to see if it was possible to have a compiled yet Ruby-like language, is now a trending language with over 7,000 github stargazers and almost 1,400 shards. Its popularity has risen considerably in the last few years, and we are incredibly proud to see something we have built resonating so much with the

Using a database is a really common task. For each kind of database there is a shard or library needed. When there is no common API to talk to a database, building more advanced shards like orm or migrations is harder. Either you end up supporting just a driver or you need to create a whole ad-hoc solution. Lacking a common api also means that when changing from one DB to another you will need to

Top Level Namespace Included Modules Spec::Expectations Spec::Methods Extended Modules Spec::Expectations Spec::Methods Defined in: Constant Summary ARGF = IO::ARGF.new(ARGV, STDIN) An IO for reading files from ARGV. Usage example: program.cr: puts ARGF.gets_to_end A file to read from: (file) 123 $ crystal build program.cr $ ./program file 123 $ ./program file file 123123 $ # If ARGV is empty, ARG

Crystal 0.20.0 has been released! Aside from the usual bugfixes and some performance improvements there’s a lot of new stuff here. Shards 0.7.0 Crystal 0.20.0 comes with version 0.7.0 of shards, mostly maintained by Julien Portalier, whichs has a few new goodies like a build command and informational crystal (version) and libraries entries in the shard.yml file. Support for GitLab dependencies was

Packages for Crystal releases are available from different sources. There are official ones provided the Crystal project, system packages and community-maintained packages. This page gives an overview of available installation methods. Linux Many Linux distribution provide Crystal in their system packages. It might not be the most recent version though. Third party package managers are typically m

Note: this was an April’s Fool post. However, with Crystal macros you could do this. We Crystal developers believe compilers should be smart. You don’t need to add type annotations everywhere: only when needed, or when you want them. Can we make the compiler even smarter? This past month we have been thinking that since Crystal is a relatively young language with a still incomplete standard librar

Crystal 0.17.0 has been released! This release includes a bunch of nice features: named tuples, double splats, a new algorithm for method arguments, and as?. Before introducing named tuples, let’s remember what tuples are. Tuples You can think of a tuple as an immutable compile-time equivalent of an Array. The compiler knows its size and the type in each position. A tuple can’t be modified. # This

Crystal 0.16.0 has been released! This is a huge release that includes a major breaking change that was announced a few months ago: types of global, class and instance variables need to be a bit more explicit. This release also includes other minor breaking changes and a lot of new goodies. The new global type inference algorithm The new rules are explained in the official docs, but let’s quickly

(This post is part of Crystal Advent Calendar 2015) This Christmas eve something curious happened: we were happily coding in Crystal when, one moment when we took our eyes away from the screen, a translucid figure appeared nearby. The entity approached and said: “I’m the Ghost of Christmas Past. Come with me.” We saw ourselves coding a new language that would resemble Ruby but be compiled and type

Crystal compiler does a lot of work in order to allow the programmer be more expressive, productive, and …lazy. Since 0.7.7 the compiler comes with some initials tools that will help the programmer know what the compiler is understanding from the code and to navigate through in a more interesting way. Go to implementations tool When compiling a method call, the compiler knows exactly which method

Crystal is a programming language with the following goals: Have a syntax similar to Ruby (but compatibility with it is not a goal) Statically type-checked but without having to specify the type of variables or method arguments. Be able to call C code by writing bindings to it in Crystal. Have compile-time evaluation and generation of code, to avoid boilerplate code. Compile to efficient native co