This rule is used for building Scala projects with Bazel. There are
currently four rules, scala_library, scala_macro_library, scala_binary
and scala_test.
In order to use scala_library, scala_macro_library, and scala_binary,
you must have bazel 0.2.3 and add the following to your WORKSPACE file:
git_repository(
name = "io_bazel_rules_scala",
remote = "https://github.com/bazelbuild/rules_scala.git",
commit = "7b891adb975b4e3e6569b763d39ab6e9234196c9", # update this as needed
)
load("@io_bazel_rules_scala//scala:scala.bzl", "scala_repositories")
scala_repositories()To use a particular tag, use the tagged number in tag = and omit the commit attribute.
Note that these plugins are still evolving quickly, as is bazel, so you may need to select
the version most appropriate for you.
Then in your BUILD file just add the following so the rules will be available:
load("@io_bazel_rules_scala//scala:scala.bzl", "scala_library", "scala_binary", "scala_test")You may wish to have these rules loaded by default using bazel's prelude. You can add the above to the file tools/build_rules/prelude_bazel in your repo (don't forget to have a, possible empty, BUILD file there) and then it will be automatically prepended to every BUILD file in the workspace.
scala_library(name, srcs, deps, runtime_deps, exports, data, main_class, resources, scalacopts, jvm_flags)
scala_macro_library(name, srcs, deps, runtime_deps, exports, data, main_class, resources, scalacopts, jvm_flags)scala_library generates a .jar file from .scala source files. This rule
also creates an interface jar to avoid recompiling downstream targets unless
then interface changes.
scala_macro_library generates a .jar file from .scala source files when
they contain macros. For macros, there are no interface jars because the macro
code is executed at compile time. For best performance, you want very granular
targets until such time as the zinc incremental compiler can be supported.
In order to make a java rule use this jar file, use the java_import rule.
| Attributes | |
|---|---|
name |
A unique name for this target |
srcs |
List of Scala |
deps |
List of other libraries to linked to this library target |
runtime_deps |
List of other libraries to put on the classpath only at runtime. This is rarely needed in Scala. |
exports |
List of targets to add to the dependencies of those that depend on this target. Similar to the `java_library` parameter of the same name. Use this sparingly as it weakens the precision of the build graph. |
data |
List of files needed by this rule at runtime. |
main_class |
Name of class with main() method to use as an entry point
The value of this attribute is a class name, not a source file. The
class must be available at runtime: it may be compiled by this rule
(from |
resources |
A list of data files to be included in the JAR. |
scalacopts |
Extra compiler options for this library to be passed to scalac. Subject to Make variable substitution and Bourne shell tokenization. |
jvm_flags |
List of JVM flags to be passed to scalac after the
|
scala_binary(name, srcs, deps, runtime_deps, data, main_class, resources, scalacopts, jvm_flags)scala_binary generates a Scala executable. It may depend on scala_library, scala_macro_library
and java_library rules.
A scala_binary requires a main_class attribute.
| Attributes | |
|---|---|
name |
A unique name for this target |
srcs |
List of Scala |
deps |
List of other libraries to linked to this binary target |
runtime_deps |
List of other libraries to put on the classpath only at runtime. This is rarely needed in Scala. |
data |
List of files needed by this rule at runtime. |
main_class |
Name of class with main() method to use as an entry point
The value of this attribute is a class name, not a source file. The
class must be available at runtime: it may be compiled by this rule
(from |
resources |
A list of data files to be included in the JAR. |
scalacopts |
Extra compiler options for this binary to be passed to scalac. Subject to Make variable substitution and Bourne shell tokenization. |
jvm_flags |
List of JVM flags to be passed to scalac after the
|
scala_test(name, srcs, suites, deps, data, main_class, resources, scalacopts, jvm_flags)scala_test generates a Scala executable which runs unit test suites written
using the scalatest library. It may depend on scala_library,
scala_macro_library and java_library rules.
A scala_test by default runs all tests in a given target.
For backwards compatiblity it accepts a suites attribute which
is ignored due to the ease with which that field is not correctly
populated and tests are not run.
scala_repl(name, deps, scalacopts, jvm_flags)A scala repl allows you to add library dependendencies (not currently scala_binary targets)
to generate a script to run which starts a REPL.
Since bazel run closes stdin, it cannot be used to start the REPL. Instead,
you use bazel build to build the script, then run that script as normal to start a REPL
session. An example in this repo:
bazel build test:HelloLibRepl
bazel-bin/test/HelloLibRepl
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