The build cache

jank and the jank build system store the output of builds into the “target” and “build” directories. By default, the target directory is target and the build directory is target/_cache, both relative to the project.clj or current directory of the jank execution. Within Leiningen projects, the jank template automatically sets up target directories per-profile. This changes the debug profile target directory to target/debug, for example. To change the target directory with jank directly you can use the --target-dir flag. Similarly, the --build-dir flag can be used, but it’s not currently possible to change the build directory within project.clj.

There are two types of artifacts:

• Final build artifacts
  • These files are meant for your consumption and are placed within the target directory.
• Intermediate build artifacts
  • These are internal files to the jank build system and are generally not consumed directly. They are stored within the build directory.

Example trees

Leiningen project

For a Leiningen project, json-query, an example tree with a debug build looks like this:

target/
├── debug
│   ├── _cache
│   │   └── json-query
│   │       ├── x86_64-unknown-linux-gnu-211eea4be7942af843e902b894e93b6cc665b2aa6943f36f5bca4ddde080972b
│   │       │   └── json_query
│   │       │       └── main.o
│   │       └── x86_64-unknown-linux-gnu-5e3948b46dee3bb4f17fc699e821182481fb5465155bdbc359678f7e6a8db9da
│   │           └── json_query
│   │               └── main.o
│   └── json-query
└── stale
    └── leiningen.core.classpath.extract-native-dependencies

Note that there are two builds of json-query, with two different hashes. This happens when your compiler flags change.

Also note that the final executable is at target/debug/json-query.

Direct jank invocation

If you invoke jank directly to compile code, you’ll still have a target and build directory created for you. Here’s an example of compiling a local hello.jank.

.
├── hello.jank
└── target
    ├── a.out
    └── _cache
        └── x86_64-unknown-linux-gnu-deb515fb6fcde162c8cefee396e3090f348d5ec8e2d1a863abf325fa79682321
            └── hello.o