A Shell With a Richer Vocabulary

Most shells give | one job: connect the bytes written by one process to the bytes read by another. That model is durable for a reason. It is also why so many useful command lines eventually turn into a negotiation between columns, delimiters, quoting rules, and a growing collection of text-processing tools.

Quirl keeps that familiar shell intact, then adds a richer vocabulary beside it. Normal mode speaks in processes and bytes. Data mode speaks in typed values. AI mode searches local command knowledge and returns a suggestion for review. Lua handles general-purpose extension logic inside a deliberately small, resource-bounded runtime.

The important part is that Quirl does not pretend these are the same thing. Changing modes changes the grammar visibly. Crossing into Bash, an external process, JSON, or Lua is explicit in the command you can read and save.

Start where you already are

Normal mode is intentionally unsurprising:

printf 'api\nworker\njobs\n' | wc -l && echo 'pipeline: healthy'

Quoting, redirects, byte pipes, boolean lists, process status, and job control belong to the Rust shell. Semantic completion understands the command and the option being edited, but the result is still an ordinary command line you can inspect before running.

When Quirl's native grammar is not the right tool, compatibility is a named boundary rather than an imitation:

bash { cat <(printf 'Bash, on purpose.\n') }

That island runs Bash syntax as Bash. The rest of the session does not have to silently guess which shell a line was written for.

Let JSON remain data

Data mode starts with a visible mode change and a focused set of readable verbs. A JSON file becomes typed records at open, not decorated terminal text that must be parsed again:

open services.json
| where latency > 50
| sort latency desc
| select service region latency

where compares numbers as numbers. sort orders the typed field. select projects only the fields that matter. The same runtime can read JSON, CSV, YAML, TOML, filesystem entries, tar archives, or an explicitly adapted external command. Every adapter carries concrete byte, row, field, depth, and materialization limits.

This is not a promise of a sprawling new programming language at the prompt. It is a bounded data pipeline for the work shells routinely make awkward.

Search by intent, run by choice

AI mode is local command retrieval, not an agent silently operating the shell. Type an outcome such as:

copy a directory while preserving permissions

Quirl searches the same semantic catalog used by completion, help, documentation, and agent exports. Selecting a result inserts it into Normal mode. It does not execute the suggestion. That review step is part of the product contract, not a temporary safety prompt.

Extend one small boundary

Lua 5.4 is Quirl's single extension language for configuration, scripts, prompts, completion providers, and trusted plugins:

return { answer = 6 * 7, sandboxed = true }

Every VM runs with a memory limit, instruction budget, wall deadline, and cancellation. The standard library is restricted, and values are converted into typed Rust structures and validated before higher layers use them. Rust owns process execution and performance-critical paths; Lua owns extension logic within the capabilities the host grants.

Small enough to inspect, tested like a shell

The measured 0.1 release artifact is 4.46 MiB and reached the first prompt in 19.2 ms P95 in its recorded release environment. The current repository has more than 1,100 Rust tests, plus real-PTY journeys, guest-side Lua tests, and bounded differential cases against available Bash and Zsh references.

Those numbers matter less as trophies than as constraints. A shell owns child processes, terminal modes, history, configuration, and user data. Fast is good; restoring the terminal and reaping every child on a failure path is mandatory.

Quirl's pitch is therefore simple: familiar where it should be, explicit where it matters. Install the official release with:

brew install niklas-heer/tap/quirl

Then run quirl, press Ctrl-Space, and give the same prompt a richer vocabulary.