Overview
BuckleScript comes with a build system, bsb, that's meant to be fast, lean and used as the build system of the BuckleScript/Reason community.
Bsb provides a few templates to quickly start a new project:
bsb -init my-directory-name
To generate a Reason project:
bsb -init my-directory-name -theme basic-reason
Feel free to inspect the various files in the newly generated directory. To see all the templates available, do:
bsb -themes
The build description file is called bsconfig.json. Every BuckleScript project needs one.
To build a project, run:
bsb -make-world
Add -w to keep the built-in watcher running. Any new file change will be picked up and the build will re-run.
Note: third-party libraries (in node_modules) aren't watched, as doing so may exceed the node.js watcher count limit. If you're doing quick and dirty modifications inside node_modules, you have to do bsb -clean-world -make-world to rebuild them.
Note 2: The watcher clears the screen with each rebuild. To suppress this, set the environment variable BS_WATCHNOCLEAR to some truthy value: BS_WATCHNOCLEAR=1 npm start
Note 3: If you are developing across multiple devices, you may find the -ws configuration useful in order to have live-reloading across the network. Possible configurations are:
bsb -make-world -w -ws _(default)bsb -make-world -w -ws 0.0.0.0:9999bsb -make-world -w -ws 5000
To build only yourself, use bsb -make.
bsb -help to see all the available options.
Artifacts Cleaning
If you ever get into an unstable build for edge-case reasons, use:
bsb -clean-world
Or bsb -clean to clean only your own artifacts.
Editor Support
Bsb generates a .merlin file, used by various editor plugins under the hood to power e.g. autocomplete, type hint, diagnosis, etc.
Bonus: you can directly pipe the bsb terminal error messages into VSCode by setting the config here.
Tips & Tricks
A typical problem with traditional build systems is that they're not resilient against the user moving/deleting source files. Most don't clean up the old artifacts correctly after such user action*. Bsb is unfortunately no different, unless you turn on "suffix": ".bs.js" in bsconfig.json, in which case we can track which JS artifact belongs to which source file correctly, even against source file moving/deletion.
Design Decisions
* One such build system that tracks these correctly & efficiently is Tup. See the (rather accessible!) paper here. Unfortunately, Tup's implementation uses FUSE and other systems, which we can't safely use on every platform.