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RuneRune

Parameters

How tasks take input. Part of the guides; full syntax in the language guide.

Concept

Section titled “Concept”

A task can accept parameters: defaulted, required, or variadic. Parameters are interpolated into the body with {{ }}, and they also define the input schema when the task is exposed to an agent over MCP.

Syntax

Section titled “Syntax”
# Defaulted — rune greet  /  rune greet Ada
greet name="world":
    @echo "hello "{{quote(name)}}


# Required — rune deploy prod
deploy env:
    @echo "deploying to "{{quote(env)}}


# Variadic — one-or-more (+) and zero-or-more (*)
test +packages:
    @echo go test {{quote_each(packages)}}


# Raw: the value is split into shell words on purpose. rune check "-v -race"
check flags:raw="-v -race":
    @echo go test {{flags}} ./...

Run them: rune greet Ada, rune deploy prod, rune test ./... ./cmd/.... quote_each(packages) passes each package as its own quoted argument, so a path that contains a space stays one argument. flags:raw declares that the value is meant to be split into words, so rune check "-v -race" passes two flags.

Runnable example

Section titled “Runnable example”

See examples/parameters.

Pitfalls

Section titled “Pitfalls”
  • Required parameters are checked before anything runs. Calling a task (or depending on one) with too few arguments fails static analysis with an arity error and exit code 3 — e.g. task "greet" expects at least 1 argument(s), got 0. See Troubleshooting.
  • A variadic must be last. Only the final parameter may be +/*.
  • Quote values with spaces on the command line, as your shell requires.
  • Interpolate parameters with quote(). {{name}} pastes the value into the command as shell text, so a space, quote, or ; in it changes the command, even inside shell quotes. rune analyze warns about this (RUNE2017). Write {{quote(name)}}, or {{quote_each(name)}} for a variadic, outside any shell quotes; declare name:raw when you want the value split into words. See Quoting parameters.

Next steps

Section titled “Next steps”