Skip to content

desic Command-Line Tool

The desic command-line tool is your primary interface for working with Desi code.

Commands

desic watch - Development Mode 🔥

Watch for file changes and automatically rebuild/run.

macOS and Linux only

desic watch is not available on Windows. It relies on Unix signals (SIGUSR1) and shared-library (.so) reloading, neither of which has a Windows implementation yet. Running it there prints a message and exits rather than watching anything. Every other desic command — run, build, test, check, fmt, doc — works on all three platforms.

desic watch           # Watch and type-check only
desic watch --run .   # Watch, build, and run with auto-restart
desic watch --hot .   # True hot reload (no process restart)
desic watch -v .      # Verbose mode

Modes:

Flag Description
(none) Type-check only on file change
--run Rebuild and restart process on change
--hot Recompile .so, reload via desi-host (no restart)

State Serialization Builtins (for --run mode):

if is_reload():
    let saved = read_state()
    if saved is Some(json):
        restore_from_json(json)
        delete_state()
else:
    print("First run")
Function Description
is_reload() true if this is a reload
reload_count() Number of reloads (0 = first)
write_state(json) Save state to temp file
read_state() Load state from temp file

Press Ctrl+C to stop watching.

desic build - Compile to an Executable

desic build hello.desi              # -> build/output/hello
desic build hello.desi -o hello     # -> ./hello
desic build hello.desi -o dist/app  # -> dist/app
desic build hello.desi -o hello -O2 # optimized

-o is a path, as it is for cc, go and rustc: the executable is written exactly where you name it, and any directories in the path are created. Without -o, the output goes to build/output/ named after the source file.

On Windows a .exe extension is appended when the path has none, since Windows will not run a file without it.

Run without a file argument to build the project described by desi.mod.

desic run - Compile and Run

desic run hello.desi
desic run hello.desi -- arg1 arg2   # arguments after -- go to the program

Compiles to a temporary location and executes it; nothing is left behind.

desic check - Type Check

Verify your code without compiling:

desic check main.desi

desic fmt - Format Code

Auto-format your Desi code with consistent style:

desic fmt -w main.desi     # Write in place
desic fmt -l ./src         # List files to change
desifmt main.desi          # Standalone formatter (stdout)
desifmt -w main.desi       # Standalone formatter (in-place)

What the formatter does:

  • Uses tabs for indentation
  • Preserves standalone comments and trailing comments
  • Preserves string literals exactly (quotes, escapes, f-strings)
  • Normalizes spacing around operators and keywords

desic doc - Generate Docs

Create Markdown documentation:

desic doc main.desi        # Public declarations
desic doc --all main.desi  # All declarations

Quick Start

# Create a file
echo 'print("Hello!")' > hello.desi

# Check it
desic check hello.desi

# Start developing with auto-reload
desic watch .

See Also