CLI / REPL

The omega binary (also aliased omega-lisp) launches a REPL or executes a one-shot expression. Internally it dispatches to dist/omega-repl.mjs.

CLI flags

Flag	Purpose
--cmd "<expr>"	evaluate one expression and exit
--file <path>	execute a .lisp file and exit
--session <name>	use the named session (~/.omega-sessions/repl-<name>.json)
--profile <name>	install a named profile for the run
--driver <name>	force a specific inference driver
--model <name>	override the model
--emacs	start in Emacs-friendly REPL mode
--no-history	disable session writing

pnpm omega-fast                                            # interactive
pnpm omega-fast -- --cmd "(+ 1 2)"                         # one-shot
pnpm omega-fast -- --session mywork --cmd "(define x 42)"
pnpm omega-fast -- --file demo/lisp/ch00-instant-showcase.lisp

Sessions are saved at ~/.omega-sessions/repl-<name>.json.

Meta-commands

REPL commands begin with :. The full set is enumerated by :help. By bucket:

Help / discovery

Command	Purpose
:help	show all commands
:help <package>	tutorial for a package
:doc <fn>	one-screen reference for a primitive
:apropos <pattern>	search by name or description
:packages	list loaded user packages
:primitives	list all 13 standard packages with primitive counts
:man <topic>	full manual page

Session

Command	Purpose
:session save <name>	save the current session as <name>
:session load <name>	load and replay session <name>
:session goto <n>	restore environment as of event N
:session list	enumerate sessions on disk
:trace	print the current session's event log

Snapshots

Command	Purpose
:save <name>	snapshot evaluator state
:restore <name>	restore from a snapshot

Debugging / time travel

Command	Purpose
:debug	enter the debugger
:step	step the machine one transition
:break <pattern>	set a breakpoint on op or AST pattern
:state	print current (C, E, S, K)
:back	step backwards (replay-aware)
:goto <n>	jump to event N

Agentic mode

Command	Purpose
:ask <prompt>	enter agentic mode — LLM has REPL as a tool, up to 20 turns
:opr-list	list available OPR kernels
:opr-run <name> <json>	run a structured OPR kernel

Utility

Command	Purpose
:quit	exit
:reset	reset evaluator state
:clear	clear screen

Exit codes

Code	Meaning
0	success — --cmd/--file ran without error
1	evaluation failed — see error output
2	bad CLI args

See also

• REPL
• Forms
• Error codes

Source: projects/omega-lisp/bin/omega.mjs (dispatch wrapper), projects/omega-lisp/bin/omega-repl.ts and projects/omega-lisp/bin/omega.ts (TS sources), projects/omega-lisp/src/repl/commands/ (per-command implementations). Live list: :help in the REPL.