Shapeshift

Experimental: this can change at any time

Shapeshift is experimental. The language, the shifty shape commands, the shifty.experimental.shapeshift Python module, and the shifty-experimental Rust crate can change in any release, without a deprecation period. Pin the Shifty version if you depend on them.

SHACL in Turtle is hard to read and harder to write. One requirement becomes a nest of blank nodes, and a failure report points at a blank node instead of the rule you meant.

Shapeshift is a short language for the same shapes. A .shm file is a list of requirements, one per line:

base <urn:example/building/>
prefix brick: <https://brickschema.org/schema/Brick#>

doc "A VAV box: fed by one AHU, with an airflow sensor."
shape vav for every brick:VAV {
  fed: brick:isFedBy exactly 1, each a brick:AHU
  flow: brick:hasPoint at least 1 is a brick:Air_Flow_Sensor
}

It compiles to the same shape algebra as SHACL, so it validates exactly like the equivalent SHACL. Failures are reported against the line you wrote. shifty shape export writes readable SHACL Turtle for other tools.

You can write Shapeshift two ways:

• As text, in .shm files, with the shifty shape commands.

• From Python, with shifty.experimental.shapeshift. Use this when shapes come from data, or to share pieces between files with Python imports.

From Rust, use shifty_experimental::shapeshift in the shifty-experimental crate. The other crates under crates/experimental/ are its implementation, not an interface.

Writing shapes	Write a shape, validate a building against it, and read the failure.
The Shapeshift language	The whole language, from files down to single tests.
Shapeshift in Python	Write Shapeshift modules from Python.
Shapeshift reference	The SHACL for each construct, reserved words, and commands.

For a larger example, see examples/shapeshift/g36/ in the repository: the ASHRAE Guideline 36 sequences, written in Python and generated as .shm files.