MPS: Skill for Claude Code

MPS Quotations and Anti-quotations

Loading companion skills

Companion names in this skill are lazy dependencies: load only those relevant to the current task. If this skill came from an MCP server, use the host's skill loader to resolve the companion's unique discovered entry URI on the same host-assigned originating server. If the host has no server-backed skill loader, stop and report that limitation; do not silently fall back to a filesystem copy. If this skill came from a filesystem catalog, load the named sibling from that same catalog at <skills-root>/<skill-name>/SKILL.md, even if remote skill loaders are also available. Do not invent a tool name or server endpoint.

A quotation is a node literal — a concise expression that evaluates to an SNode (or tree of SNodes) at runtime. Instead of building nodes manually via the smodel API, you write the desired structure in the target language syntax and let MPS wrap it. Anti-quotations ("antiquotations") are escape holes inside a quotation where a runtime expression is spliced in.

Required used language: jetbrains.mps.lang.quotation (UUID 3a13115c-633c-4c5c-bbcc-75c4219e9555)

Critical Directives

• Quotations do not call behavior constructors. Using <Car()> produces an SNode of concept Car without running its constructor. Use new node<Car>() (smodel API) when you need the constructor to run.
• Use the concept identifier inside a quotation, not an alias. Write <IntegerType>, not <int>.
• All four anti-quotation kinds attach via the inherited smodelAttribute role on any BaseConcept. The anti-quotation node is a sibling attribute of the host node, not a replacement child. The runtime substitution happens during materialisation. See references/antiquotations.md.
• ListAntiquotation constraint: the list role must contain at least one placeholder child before you can activate a list antiquotation. The placeholder is replaced at runtime with zero-or-more nodes.
• PropertyAntiquotation.propertyId and ReferenceAntiquotation.linkId are filled in automatically by MPS when you type $ / ^ in a property/reference cell. Do not construct these encoded ids manually unless you have already verified the exact language-uuid/concept-id/property-or-link-id form against the running MPS. See references/property-and-reference-ids.md.
• Prefer heavy quotation (<...>) for readability; switch to light quotation (NodeBuilder) only for bootstrapping (the target language can't be a used language), for generators-of-generators, or when nesting depth makes embedded syntax unreadable. See references/heavy-vs-light.md.
• The deprecated NodeBuilderInitLink.expression (cardinality 0..1) was removed in 2019.2. Use initValue with a NodeBuilderExpression instead.
• Edit quotation-bearing models through MPS MCP tools (mps_mcp_insert_root_node_from_json, mps_mcp_update_node). Do not hand-edit .mps files.
• Validate with mps_mcp_check_root_node_problems; quotations frequently expose missing used-languages on the host model (the quoted concept's language must be a used language, not just a dependency).