How to write and release Crystal Shards.
What's a Shard?
Simply put, a Shard is a package of Crystal code, made to be shared-with and used-by other projects.
See the Shards command for details.
In this tutorial, we'll be making a Crystal library called palindrome-example.
For those who don't know, a palindrome is a word which is spelled the same way forwards as it is backwards. e.g. racecar, mom, dad, kayak, madam
In order to release a Crystal Shard, and follow along with this tutorial, you will need the following:
Creating the Project
Begin by using the Crystal compiler's
init lib command to create a Crystal library with the standard directory structure.
In your terminal:
crystal init lib <YOUR-SHARD-NAME>
$ crystal init lib palindrome-example create palindrome-example/.gitignore create palindrome-example/.editorconfig create palindrome-example/LICENSE create palindrome-example/README.md create palindrome-example/.travis.yml create palindrome-example/shard.yml create palindrome-example/src/palindrome-example.cr create palindrome-example/src/palindrome-example/version.cr create palindrome-example/spec/spec_helper.cr create palindrome-example/spec/palindrome-example_spec.cr Initialized empty Git repository in /<YOUR-DIRECTORY>/.../palindrome-example/.git/
cd into the directory:
commit to start tracking the files with Git:
$ git add -A $ git commit -am "First Commit" [master (root-commit) 77bad84] First Commit 10 files changed, 102 insertions(+) create mode 100644 .editorconfig create mode 100644 .gitignore create mode 100644 .travis.yml create mode 100644 LICENSE create mode 100644 README.md create mode 100644 shard.yml create mode 100644 spec/palindrome-example_spec.cr create mode 100644 spec/spec_helper.cr create mode 100644 src/palindrome-example.cr create mode 100644 src/palindrome-example/version.cr
Writing the Code
The code you write is up to you, but how you write it impacts whether people want to use your library and/or help you maintain it.
Testing the Code
- Test your code. All of it. It's the only way for anyone, including you, to know if it works.
- Crystal has a built-in testing library. Use it!
- Document your code with comments. All of it. Even the private methods.
- Crystal has a built-in documentation generator. Use it!
crystal docs to convert your code and comments into interlinking API documentation. Open the files in the
/docs/ directory with a web browser to see how your documentation is looking along the way.
See below for instructions on hosting your compiler-generated docs on GitHub Pages.
Once your documentation is ready and available, add this documentation badge below the description in your README.md so users know that it exists.
(Be sure to replace
[![Docs]( )]( )
Writing a README
A good README can make or break your project. Awesome README is a nice curation of examples and resources on the topic.
Most importantly, your README should explain:
- What your library is
- What it does
- How to use it
This explanation should include a few examples along with subheadings.
NOTE: Be sure to replace all instances of
[your-github-name] in the Crystal-generated README template with your GitHub username.
- It's fine to have your own style, but sticking to some core rubrics defined by the Crystal team can help keep your code consistent, readable and usable for other developers.
- Utilize Crystal's built-in code formatter to automatically format all
.crfiles in a directory.
crystal tool format
To check if your code is formatted correctly, or to check if using the formatter wouldn't produce any changes, simply add
--check to the end of this command.
crystal tool format --check
See the Travis CI section below to implement this in your build.
The spec is your rulebook. Follow it.
name property should be concise and descriptive.
- Search crystalshards.xyz to check if your name is already taken.
description to your
description is a single line description used to search for and find your shard.
A description should be:
It's hard for anyone to use your project if they can't find it. crystalshards.xyz is currently the go-to place for Crystal libraries, so that's what we'll optimize for.
There are people looking for the exact functionality of our library and the general functionality of our library. e.g. Bob needs a palindrome library, but Felipe is just looking for libraries involving text and Susan is looking for libraries involving spelling.
name is already descriptive enough for Bob's search of "palindrome". We don't need to repeat the palindrome keyword. Instead, we'll catch Susan's search for "spelling" and Felipe's search for "text".
description: | A textual algorithm to tell if a word is spelled the same way forwards as it is backwards.
Create a repository with the same
descriptionas specified in your
Add and commit everything:
$ git add -A && git commit -am "shard complete"
- Add the remote: (Be sure to replace
NOTE: If you like, feel free to replace
origin, or a remote name of your choosing.
$ git remote add public https://github.com/<YOUR-GITHUB-NAME>/<YOUR-REPOSITORY-NAME>.git
- Push it:
$ git push public master
It's good practice to do GitHub Releases.
Add the following markdown build badge below the description in your README to inform users what the most current release is:
(Be sure to replace
[![GitHub release]( )]( )
Start by navigating to your repository's releases page.
- This can be found at
Click "Create a new release".
According to the Crystal Shards README,
When libraries are installed from Git repositories, the repository is expected to have version tags following a semver-like format, prefixed with a
v. Examples: v1.2.3, v2.0.0-rc1 or v2017.04.1
Accordingly, in the input that says
tag version, type
v0.1.0. Make sure this matches the
shard.yml. Title it
v0.1.0 and write a short description for the release.
Click "Publish release" and you're done!
You'll now notice that the GitHub Release badge has updated in your README.
Follow Semantic Versioning and create a new release every time your push new code to
Travis CI and
If you haven't already, sign up for Travis CI.
Insert the following markdown build badge below the description in your README.md:
(be sure to replace
[![Build Status]( )]( )
Build badges are a simple way to tell people whether your Travis CI build passes.
Add the following lines to your
script: - crystal spec
This tells Travis CI to run your tests. Accordingly with the outcome of this command, Travis CI will return a build status of "passed", "errored", "failed" or "canceled".
If you want to verify that all your code has been formatted with
crystal tool format, add a script for
crystal tool format --check. If the code is not formatted correctly, this will break the build just as failing tests would.
script: - crystal spec - crystal tool format --check
Commit and push to GitHub.
Follow these guidelines to get your repo up & running on Travis CI.
Once you're up and running, and the build is passing, the build badge will update in your README.
docs on GitHub-Pages
Add the following
script to your
- crystal docs
This tells Travis CI to generate your documentation.
Next, add the following lines to your
(Be sure to replace all instances of
deploy: provider: pages skip_cleanup: true github_token: $GITHUB_TOKEN project_name: <YOUR-GITHUB-REPOSITORY-NAME> on: branch: master local_dir: docs
If you've been following along, your
.travis.yml file should look something like this:
language: crystal script: - crystal spec - crystal docs deploy: provider: pages skip_cleanup: true github_token: $GITHUB_TOKEN project_name: <YOUR-GITHUB-REPOSITORY-NAME> on: branch: master local_dir: docs
Click Here for the official documentation on deploying to GitHub-Pages with Travis CI.