alonsodomin / cron4s   0.7.0

Contributors Wanted Apache License 2.0 Website GitHub

Cross-platform CRON expression parsing for Scala

Scala versions: 3.x 2.13 2.12
Scala.js versions: 1.x
Scala Native versions: 0.4


Join the chat at Build Status Scala.js License Maven Central

Codacy Badge codecov Mergify Status

Idiomatic Cron expression parsing in Scala and ScalaJS.


Please, take a look at the user guide for instructions on how to use this library. The remaining of this section will be focused on information for other developers.


cron4s is built using SBT:

git clone
cd cron4s
sbt test

The user documentation is built/generated using sbt-microsites and requires Jekyll to be installed in the local machine. To generate and browse the latest docs from master follow these steps from the project's root folder:

sbt makeMicrosite
cd docs/target/site
jekyll serve

Then make your browser point to and that's all.

Cross building

cron4s is cross-built and published for several versions of Scala. The different set of versions are configured in the build.sbt file in the crossScalaVersions setting. We use the SBT Github Actions plugin to generate Github Actions workflows that are in sync with what has been specified in the build.sbt file.

Supporting additional Scala versions is a matter of adding a new version to that setting and then make the codebase compile against it whilst preserving backwards compatibility. The easiest way to check that compatibility is triggering a cross build with SBT:

sbt +test

When making changes to the build.sbt file, it is highly recommended to run the sbt githubWorkflowGenerate command to ensure that the Github Actions workflows are based on the latest updates.

Repository Automation

There is some sort of automation configured in this repository to ease the management of some tedious or repetitive tasks:

  • Version upgrades: The Scala Steward will be producing pull requests with version upgrades of this library dependencies.
  • Auto-merge: Mergify is installed in this repo to do auto-merge of pull requests that meet a given criteria. This said criteria can be modified in the .mergify at the project's root folder.
  • CI Release: A Github Actions workflow has been configured, not just to build the project, but also to be able to release to Maven Central with minimal user interaction. Pushing a tag in the repo with the version number will sign and publish such a release in Maven Central, non-tagged commits to master will be published as SNAPSHOT.

Related Projects

This is a non-exhaustive list of other open source projects and libraries that use or are somewhat related to Cron4s. If you have a library that depends on Cron4s you could add it here:

  • fs2-cron: Create pure functional streams that emit elements based on a given cron schedule.
  • pureconfig-cron4s: Cron expression parsing support in configuration files.

Code Of Conduct

See the Code of Conduct.


Copyright 2017 Antonio Alonso Dominguez

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

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.