#Scala Exercises
"Scala Exercises" brings exercises for the Stdlib, Cats, Shapeless and many other great libraries for Scala to your browser. Offering hundreds of solvable exercises organized into several categories covering the basics of the Scala language and it's most important libraries.
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LEARN: Each category includes an explanation of the basics. Learn the concepts through simple code samples.
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SOLVE: Each exercise is a unit test that must pass successfully, complete the exercise by filling in the blanks. Receive instant feedback as your answers are validated in real-time.
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SHARE: The system will consider the category complete when all its exercises are successfully done. Don't forget to share your progress on social networks before moving on to the next category!
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EDIT: After completing a category, you'll be able to go back and edit it. Add new exercises or improve existing ones by sending a pull-request.
Scala Exercises is available at scala-exercises.org.
- Install JDK 8, either the Oracle version or OpenJDK
- Install Scala
- Install SBT
- Install PostgreSQL 9.4
- Install the Sass Ruby gem and make sure the
sass
program can be run
First of all, either clone the repository via git
$ git clone https://github.com/scala-exercises/scala-exercises
or download it
$ wget https://github.com/scala-exercises/scala-exercises/archive/master.zip
You'll need a working PostgreSQL 9.4 database and user for running the app. Once the database is running,
- Create a user called
scalaexercises_dev_user
$ sudo -u postgres psql -c "CREATE USER scalaexercises_dev_user WITH PASSWORD 'a_password';"
- Create a db called
scalaexercises_dev
and grant all privileges on it toscalaexercises_dev_user
$ sudo -u postgres createdb scalaexercises_dev
$ sudo -u postgres psql -c "GRANT ALL PRIVILEGES ON DATABASE scalaexercises_dev TO scalaexercises_dev_user;"
Edit the site/server/conf/application.dev.conf
configuration file with your database information.
Go into the project's root directory, run sbt run
$ sbt run
After compilation the application will be running, listening in the 9000 port. Point your browser
to localhost:9000
and start having fun!
If you use ensime and you have configured the sbt-ensime
plugin in your sbt user
global settings, likely you might have this issue running the application locally:
java.lang.NoClassDefFoundError: scalariform/formatter/preferences/SpacesAroundMultiImports$
In that case, you could solve this issue setting up your /.sbt/0.13/plugins/plugins.sbt
file
as follow:
addSbtPlugin("org.ensime" % "ensime-sbt" % "0.5.1")
dependencyOverrides in ThisBuild += "org.scalariform" %% "scalariform" % "0.1.8"
In order to avoid the error related to Github API rate limit exceeded
during compilation of exercises, we recommend setting locally an environment variable called GITHUB_TOKEN
with a personal token which you can create here.
The project is split between a few directories, namely:
server
, which contains the server code written using Play,client
, which contains ScalaJS code for a frontend part of the application,shared
, where code shared between the server and the client exists,definitions
, containing definitions used by other parts of the application and libraries containing exercises,sbt-exercise
is a sbt plugin which locates exercise libraries and processes their source code,compiler
for compiling exercises,runtime
for runtime evaluation of exercises.
The compiler
and runtime
directories allow exercises to be defined using
regular Scala which is compiled into an exercise library.
The site
, client
and shared
directories contain the website. These items depend on components in compiler
and runtime
.
At the moment, those subprojects are coupled tightly. Once this project is a bit more stable the exercise compiler plugin will be published and it will be easy to create new exercises for existing Scala libraries.
Contributions welcome! Please join our Gitter channel to get involved.
Feel free to open an issue if you notice a bug, have an idea for a feature, or have a question about the code. Pull requests are also gladly accepted.
People are expected to follow the Typelevel Code of Conduct when discussing Scala Exercises on the Github page, Gitter channel, or other venues.
We hope that our community will be respectful, helpful, and kind. If you find yourself embroiled in a situation that becomes heated, or that fails to live up to our expectations, you should disengage and contact one of the project maintainers in private.
##License
Copyright (C) 2015-2016 47 Degrees, LLC. Reactive, scalable software solutions. http://47deg.com [email protected]
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.