cue-lang

# CUE (+1) > Configuration, data validation, and code generation via lattice unification. **Trit**: +1 (PLUS - generative type lattice) **Language**: Go **Branch**: `master` ## Core Insight: Values ARE Types ```cue // In CUE, every value is also a type constraint name: string // type constraint name: "alice" // concrete value IS a subtype // Unification: greatest lower bound a: {x: int, y: string} b: {x: 1, z: bool} c: a & b // → {x: 1, y: string, z: bool} ``` ## Lattice Type System ``` ⊤ (any) / | \ int str bool | | | 1 "a" true \ | / ⊥ (error) Unification = Greatest Lower Bound (GLB) int & 1 → 1 int & string → ⊥ (error) ``` ## Key Features | Feature | CUE | JSON Schema | TypeScript | |---------|-----|-------------|------------| | Values = Types | ✓ | ✗ | ✗ | | Unification | ✓ | ✗ | ✗ | | Constraints | ✓ | Partial | Partial | | Code gen | ✓ | ✗ | ✗ | | Turing-complete | ✗ | ✗ | ✓ | **CUE is intentionally NOT Turing-complete** - guarantees termination. ## Syntax Essentials ```cue package myconfig import "list" // Definitions (templates) #Person: { name: string age: int & >=0 & <=150 email: =~"^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$" } // Concrete values alice: #Person & { name: "Alice" age: 30 email: "alice@example.com" } // List comprehensions numbers: [1, 2, 3, 4, 5] doubled: [for x in numbers {x * 2}] // Disjunction (sum types) Status: "pending" | "active" | "complete" ``` ## Schema Integration ```bash # CUE → JSON Schema cue export --out jsonschema schema.cue # CUE → OpenAPI cue export --out openapi api.cue # Go types → CUE cue get go ./pkg/... # Validate YAML/JSON against CUE cue vet data.yaml schema.cue ``` ## Comparison with Nickel | Aspect | CUE | Nickel | |--------|-----|--------| | Type system | Lattice unification | Gradual typing + contracts | | Evaluation | Lazy, no side effects | Lazy, pure | | Turing-complete | No (terminates) | Yes | | Error messages | Structural | Blame tracking | | Primary use | K8s/Cloud config | General config | ## Sexp Bridge ```cue // CUE can export to various formats output: json.Marshal(config) // → JSON output: yaml.Marshal(config) // → YAML // For sexp, use external tool: // cue export config.cue | json2sexp ``` Integration with lispsyntax-acset: ```julia # Julia: parse CUE output, convert to sexp using JSON3, LispSyntax cue_json = read(`cue export config.cue`, String) data = JSON3.read(cue_json) sexp = json_to_sexp(data) # Custom bridge ``` ## GF(3) Config Triad ``` CUE (+1) + Nickel (0) + Hof (-1) = 0 ✓ generative ergodic extractive schemas contracts code gen ``` ## Sexp Neighborhood | Skill | Trit | Bridge to CUE | |-------|------|---------------| | **hof** | -1 | Consumes CUE, generates code | | **nickel** | 0 | Alternative with contracts | | **lispsyntax-acset** | 0 | CUE → JSON → sexp → ACSet | | **geb** | +1 | Both use algebraic types | | **gay-mcp** | +1 | Color CUE schema elements | ## Usage ```bash # Install go install cuelang.org/go/cmd/cue@latest # Evaluate cue eval config.cue # Export to JSON cue export config.cue # Validate cue vet data.yaml schema.cue # Format cue fmt *.cue # Get Go types cue get go ./... ``` ## Kubernetes Example ```cue package k8s import "k8s.io/api/apps/v1" #Deployment: v1.#Deployment & { apiVersion: "apps/v1" kind: "Deployment" metadata: { name: string namespace: string | *"default" } spec: { replicas: int & >=1 & <=100 | *3 selector: matchLabels: app: metadata.name template: { metadata: labels: app: metadata.name spec: containers: [...#Container] } } } #Container: { name: string image: string ports: [...{containerPort: int}] } ``` ## CLI Commands ```bash # Core commands cue eval # Evaluate and print cue export # Export to JSON/YAML/etc cue vet # Validate data cue def # Print definitions cue fmt # Format files cue get # Import from Go/Proto cue mod # Module management cue trim # Remove redundant values ``` --- ## End-of-Skill Interface ## Related Skills | Skill | Trit | Relationship | |-------|------|--------------| | hof | -1 | CUE consumer for codegen | | nickel | 0 | Alternative approach | | geb | +1 | Algebraic type sibling | | acsets | 0 | Schema → ACSet bridge | --- **Trit**: +1 (PLUS - generative lattice) **Key Property**: Unification-based config with guaranteed termination **Philosophy**: Values ARE types, constraints compose via GLB --- ## Autopoietic Marginalia > **The interaction IS the skill improving itself.** Every use of this skill is an opportunity for worlding: - **MEMORY** (-1): Record what was learned - **REMEMBERING** (0): Connect patterns to other skills - **WORLDING** (+1): Evolve the skill based on use *Add Interaction Exemplars here as the skill is used.*