🥮 skills.mooncakes.ioexperimental

mpkl

// Use mpkl to parse, typecheck, evaluate, or normalize Apple Pkl files and inline source in a WebAssembly command. Use when an agent needs to validate a local Pkl file tree with relative imports or cached package:// dependencies, inspect evaluated configuration as PCF, JSON, YAML, properties, plist, textproto, XML, or Jsonnet, or compare a small Pkl snippet without installing Apple Pkl.

moon runwasm

moon runwasm mizchi/pkl@0.6.0/cmd/mpkl

$ files

SKILL.md

readonly

mpkl

Run mpkl through the MoonBit Skills Marketplace when a task needs a quick, local check of Pkl source or a local Pkl file tree.

Run

Pass a file path to load it from the current working directory. Relative import, expression-level import(), extends, and amends dependencies are loaded recursively:

moon runwasm mizchi/pkl/cmd/mpkl -- check config.pkl
moon runwasm mizchi/pkl/cmd/mpkl -- eval --format json config.pkl

package:// dependencies are resolved from a pre-extracted mpkl package cache. Pass a cache explicitly when it is not in the default location:

moon runwasm mizchi/pkl/cmd/mpkl -- eval --format json \
  --package-cache .pkl-packages Taskfile.pkl

--package-cache is repeatable. Without it, mpkl checks $PKL_MBT_PACKAGE_CACHE, $XDG_CACHE_HOME/pkl-mbt/package-2, then $HOME/.cache/pkl-mbt/package-2. Populate the cache first with the native mpkl CLI; the Wasm command does not download a cache miss.

For a small self-contained module, pass the complete text with --source:

moon runwasm mizchi/pkl/cmd/mpkl -- eval --format json --source 'answer = 6 * 7'

Use one of these commands:

parse: validate syntax and print ok.
check: parse and typecheck the module, then print its inferred type.
eval: evaluate the module and render its value. Select pcf, json, yaml, properties, plist, textproto, xml, or jsonnet with --format; the default is pcf.
format: evaluate the module and emit canonical PCF. Treat this as value normalization, not as a comment-preserving source formatter.

When using --source, preserve newlines and quote the argument so the shell does not interpret Pkl interpolation or punctuation.

Constraints

File paths are host paths resolved from the process working directory. Without a Moonrun policy, the command inherits Moonrun's legacy filesystem access. For an agent or untrusted project, pass a deny-by-default policy that exposes only the required tree:

[fs]
read = ["config"]

moon runwasm --experimental-policy moonrun-policy.toml \
  mizchi/pkl/cmd/mpkl -- eval config/main.pkl

File mode resolves package:// and projectpackage:// URIs only from an already extracted package cache. It does not fetch HTTP or a missing package, and does not currently expand import globs or provide Pkl resource reads and environment properties. Use the native mpkl CLI to populate a package cache or when the task needs those capabilities.

Interpret exit codes as follows: