CLI reference

Usage: jazz [--run] [options] [source.jz]
       jazz [--run] --entry-module Module::Path [--module-root DIR...] [options]

Modes and source selection

Form	Behavior
no source or -	read standalone source from stdin
source.jz	read one standalone source file
--entry-module A::B	load a module graph; default root is .
--run	evaluate and print the final value
no --run	parse and analyze; clean success is quiet

Repeated --module-root DIR flags preserve order and require an entry module. A source selector and entry module are mutually exclusive.

Prelude and warnings

--prelude PATH selects an explicit Prelude; --no-prelude disables it. They cannot be combined. JAZZ_PRELUDE is used only when neither CLI form selects a Prelude.

Warning controls include -Wcategory, -Wno-category, -Werror=category, -Werror, and -Wnone. --warnings-config PATH selects a config file. Resolution precedence is CLI, environment, project config, then the silent default. Environment variables are JAZZ_WARNING_FLAGS, JAZZ_WARNING_ERROR_FLAGS, and JAZZ_WARNING_CONFIG; the default project file is .jazz-warnings.

Runtime observations

--runtime-stats, --runtime-stats=human, and --runtime-stats=json report deterministic semantic statistics on stderr. --runtime-profile=PATH writes a deterministic Speedscope profile atomically. These options require --run.

--help and -h print help to stdout without reading source, Prelude, or configuration files. After successful run-mode evaluation, IO.exit! may request any process status from 0 through 255; that status becomes the CLI status and suppresses the final-value print. Invalid arguments and required-file read failures exit with status 2; compile or runtime diagnostics exit with status 1. See diagnostics.