Wrath is a simplistic source-based build script for Scala, written in Bash, with only limited functionality intended for bootstrapping projects which don't want to rely upon a more complex tool. It was written primarily to build Fury, and understands a minimal subset of Fury builds.

Running a build is typically as simple as running the wrath command in a directory containing a fury file,

wrath

which will compile the default module (if there is one), or offer advice on any additional parameters that may be required.

Several other parameters can also be specified:

• --target <module> (-t) — specify a different target module
• --exec (-x) — execute the main method for the target module
• --repl (-r) — launch the REPL with the target module on the classpath
• --clean (-c) — clean the target module before rebuilding
• --deep-clean (-c) — clean and rebuild all sources
• --fetch (-f) — fetch any source repositories required by the build
• --fetch-all (-F) — fetch the Scala compiler as well
• --main <class> (-m) — specify the main class to invoke (with -x)
• --jdk <dir> (-j) — specify a different JAVA_HOME directory
• --help (-h) — print a usage information

Dependent repositories are referenced as subdirectories of the project root directory. Running Wrath with the -f parameter will fetch any missing dependencies, but symbolic links can be used to point Wrath to a directory elsewhere on disk.

The Scala compiler is similarly a dependency, and will be kept in the scala subdirectory. It's common to want to use a single copy of the Scala compiler for all projects, and is most easily specified with a symlink. Scala will only be fetched from GitHub if the -F option is specified. This may be useful in CI environments.

Configuration files are called build.wrath and are written in a simple form of CoDL. A typical build file contains a project declaration,

project myproject

and one or more module declarations, for example:

project myproject
  module core
  module test

A top-level target declaration should point to the default target to compile/run when calling wrath without arguments.

A number of top-level repo declarations should

Within a module, the following may be defined:

• main — the name of the main method to invoke when running (with wrath -x)
• sources — a space-separate list of source directories
• lib — a library dependency; two parameters, an id and a URL
• include — a space-separated list of dependencies in the form, <project>/<module>
• plugin — should be set to yes if the module defines a compiler plugin

A more complete module definition might look like this:

repo acme/mylibrary
target myproject/test

project myproject
  module core
    sources  src/core
    include  mylibrary/core mylibrary/extras
    lib      servlet-api https://repo1.maven.org/maven2/javax/servlet/javax.servlet-api/3.0.1/javax.servlet-api-3.0.1.jar

  module test
    sources  src/test
    include  myproject/core
    main     myproject.Tests

Wrath stores all its working files in a directory called .wrath in the project root directory. This directory can be safely deleted (though artifacts may need to be downloaded again). All produced artifacts are stored in a directory called dist in the project root directory.