Cellar

Look up the public API of any Maven-published JVM dependency from the terminal.

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When a coding agent needs to call an unfamiliar library method, its options are bad: parse HTML docs (expensive, unreliable), find source on GitHub (requires knowing the URL), or hallucinate the API.

Cellar gives agents — and humans — a single shell command that returns exactly the type signatures, members, and docs needed to write correct code. Output is plain Markdown on stdout, ready to be injected into an LLM prompt with zero post-processing.

Supported artifacts

Format	Support
Scala 3 (TASTy)	Full — signatures, flags, companions, sealed hierarchies, givens, extensions, docstrings, source
Scala 2 (pickles)	Best-effort — type information may be incomplete
Java (.class)	Good — signatures, members, source

Usage

cellar get <coordinate> <fqn>

Look up a single symbol — type signature, flags, members, companion, known subtypes, docstring.

cellar get org.typelevel:cats-core_3:2.10.0 cats.Monad
cellar get org.apache.commons:commons-lang3:3.14.0 org.apache.commons.lang3.StringUtils

cellar get-source <coordinate> <fqn>

Fetch the source code from the published -sources.jar.

cellar get-source org.typelevel:cats-core_3:2.10.0 cats.Monad

cellar list <coordinate> <package-or-class>

List all public symbols in a package or class. Supports --limit N (default: 50).

cellar list org.typelevel:cats-core_3:2.10.0 cats
cellar list org.typelevel:cats-core_3:2.10.0 cats.Monad

cellar search <coordinate> <query>

Case-insensitive substring search across all symbol names. Supports --limit N (default: 50).

cellar search org.typelevel:cats-core_3:2.10.0 flatMap
cellar search io.circe:circe-core_3:0.14.6 decode

cellar deps <coordinate>

Print the full transitive dependency tree.

cellar deps org.typelevel:cats-effect_3:3.5.4

Coordinates

Maven coordinates must be explicit — group:artifact:version. The :: shorthand is not supported.

org.typelevel:cats-core_3:2.10.0        # Scala 3
org.typelevel:cats-core_2.13:2.10.0     # Scala 2
org.apache.commons:commons-lang3:3.14.0 # Java

Options

Flag	Description
--java-home <path>	Use a specific JDK for JRE classpath
-r, --repository <url>	Extra Maven repository URL (repeatable)
-l, --limit <N>	Max results (list and search only)

Output conventions

• stdout — Markdown content (signatures, docs, source)
• stderr — diagnostics (warnings, truncation notices)
• Exit 0 — success
• Exit 1 — error

Building

Requires JDK 17+ and Mill.

# Fat JAR
./mill cli.assembly
java -jar out/cli/assembly.dest/out.jar get org.typelevel:cats-core_3:2.10.0 cats.Monad

# Native image (GraalVM)
./mill cli.nativeImage

# Wrapper script
./scripts/cellar get org.typelevel:cats-core_3:2.10.0 cats.Monad

Running tests

# Publish test fixtures to local Maven first
./mill publishFixtures

# Run tests
./mill lib.test

Tech stack

Scala 3, Cats Effect, fs2, tasty-query, Coursier, decline, Mill.