CLI Reference

The weir CLI is the main interface for compiling and running Weir programs. It supports both single-file mode (pass a .weir file) and package mode (discover weir.pkg in the current directory).

Commands

weir run [file]

Compile and run a Weir program via Cranelift JIT.

weir run hello.weir              # single file
weir run                         # package mode (reads weir.pkg)
weir run --load libfoo.so        # pre-load a shared library

Option	Description
file	Path to .weir source file. Omit to use weir.pkg.
--load <path>	Pre-load a shared library (makes symbols available via dlsym). Repeatable.

weir build [file]

Compile a Weir program to a standalone native binary via AOT compilation.

weir build hello.weir                    # outputs ./hello
weir build hello.weir -o bin/hello       # custom output path
weir build -l glfw -l GL                 # link C libraries
weir build --cc-arg helper.c             # pass extra files to the C compiler
weir build                               # package mode

Option	Description
file	Path to .weir source file. Omit to use weir.pkg.
-o, --output <path>	Output binary path. Defaults to source file stem or package name.
-l, --link <lib>	Link against a C library (e.g. -l glfw). Repeatable.
--cc-arg <arg>	Pass raw arguments to the C compiler. Repeatable.

weir dev [file]

Run a Weir program with live reloading. Watches for file changes and hot-swaps functions without restarting.

weir dev game.weir               # watch single file
weir dev                         # package mode
weir dev --load libfoo.so        # pre-load libraries

Option	Description
file	Path to .weir source file. Omit to use weir.pkg.
--load <path>	Pre-load a shared library. Repeatable.

When a file changes:

1. The source is re-read, re-lexed, re-parsed, and re-typechecked
2. Changed functions are recompiled via Cranelift
3. Function pointers are swapped in the running program
4. Execution continues with the new code

If the new code has errors, the old version keeps running and errors are reported.

weir check <file>

Type-check a Weir file without running it.

weir check hello.weir

Outputs OK — no type errors on success, or type errors with locations on failure.

weir parse <file>

Parse a Weir file and dump the AST. Useful for debugging the parser.

weir parse hello.weir

weir interp <file>

Run a Weir file via the tree-walking interpreter. Slower than JIT, but useful for debugging and testing.

weir interp hello.weir

weir expand <file>

Expand macros and print the resulting source. Like cargo expand for Rust.

weir expand hello.weir

weir lsp

Start the Weir Language Server Protocol server. Typically invoked by an editor, not directly.

weir lsp

Package Mode

When run, build, or dev are invoked without a file argument, the CLI looks for a weir.pkg manifest in the current directory:

cd demos/tetris
weir run                         # discovers weir.pkg, resolves deps, runs via JIT
weir build -o ../../tmp/tetris   # AOT compile the package
weir dev                         # dev mode with live reload

The package system:

1. Parses weir.pkg for metadata, sources, and dependencies
2. Recursively resolves path-based dependencies
3. Topologically sorts the dependency graph
4. Validates import statements against actual module exports
5. Compiles native C sources (if any) into a shared library
6. Concatenates all sources and runs the standard pipeline

See Package System for details.