README
get_moonhome
#get_moonhome
A minimal MoonBit module demonstrating how to run build.mbtx with the
module-level --moonbit-unstable-prebuild option. It uses only the standard
library and requires no third-party dependencies.
#Run
cd /Users/yorkin/source/moonbit/bin_deps_test/get_moonhome
moon build
moon run .moon.mod sets the default target to native. Running the module prints the
script's diagnostic message followed by the main program's output, for example:
[prebuild] MOON_HOME=/Users/yorkin/.moon
get_moonhome: main executedMoon may also print build progress and notices about experimental scripts.
#Configuration and script
The key configuration is in moon.mod:
options(
"preferred-target": "native",
"--moonbit-unstable-prebuild": "build.mbtx",
)The script path is relative to the module root. Moon automatically compiles the
.mbtx file to linear-memory Wasm and executes it with moonrun. No separate
moon run command is needed in the configuration.
build.mbtx reads the inherited environment variable with
@env.get_env_var("MOON_HOME"). If it is unset, the script falls back to
HOME/.moon, or USERPROFILE/.moon when HOME is unavailable. This fallback is
implemented by the example script; Moon does not automatically inject a default
MOON_HOME. Set the environment variable explicitly for a nonstandard location.
The script's stdout must contain exactly one build configuration JSON value,
for example:
{"vars":{"MOON_HOME":"/Users/yorkin/.moon"}}This example prints the path to stderr with eprintln and returns JSON on
stdout with println(output.stringify()). The returned variable can be
referenced as ${build.MOON_HOME} in build configuration. It does not
automatically become an environment variable in the main program, which only
demonstrates the normal build and run flow in this example.
You can also run the script directly to inspect the returned JSON:
moon run --target wasm build.mbtx#When the script runs
- This is an experimental module-level configuration script option. Its full name is --moonbit-unstable-prebuild.
- native and llvm builds execute it; wasm, wasm-gc, and js builds skip it.
- moon check skips this module's configuration script. Use moon build or moon run . to verify the hook.
- Native/LLVM builds with --dry-run also execute the script to obtain the build configuration.
- Package-level pre-build or rule + dev_build entries in moon.pkg use a separate code generation mechanism.
See Moon's prebuild documentation
for implementation details.
Apache-2.0
Updated 17 days ago
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