Standard: CRG v2.0 STRICT Current Grade: D Assessed: 2026-04-12 (promoted E → D after iteration 2) Assessor: Jonathan D.A. Jewell

Grade D criterion: "Works on some inputs, test matrix present."

• Parser implemented: KRLAdapter.jl/src/parser/ (Julia, Option B decision 2026-04-12)
  • lexer.jl — full lexer with position tracking, KRLLexError
  • ast.jl — all AST node types (KRLProgram, KRLBinding, KRLGenerator, KRLCompose, KRLTensor, KRLPrefixOp, KRLParenExpr, KRLIdentifier, KRLQuery, KRLFilter, KRLIntValue, KRLStrValue, KRLIdentValue)
  • parser.jl — recursive descent, full v0.1.0 grammar
  • lower.jl — AST → TangleIR lowering with KRLLowerError
• Grammar ambiguity resolved: ; as sequential composition only fires inside parenthesised expressions (in_parens=true); at statement level ; is the terminator.
• Test matrix: KRLAdapter.jl/test/parser_test.jl — 5 testsets, 57 tests
  • Lexer: keywords, identifiers, integers, strings, operators, punctuation, comments stripped, position tracking, lex error, unterminated string
  • Parser: 20 grammar cases including all generators, let bindings, sequential compose (with parens), tensor product, prefix ops, queries with and chains
  • Parser errors: missing ;, unrecognised token, missing index, zero index
  • Example .krl files: all 4 examples in krl/examples/ parse without error
  • Lowering: sigma/sigma_inv → TangleIR, compose, trefoil, mirror, let binding, unbound identifier error, query → KRLQueryPlan
• 5577 tests pass (full KRLAdapter.jl suite including parser tests)

The implemented grammar (v0.1.0):

• No typechecker. Port-arity compatibility (e.g. composing a 2-strand braid with a 3-strand tangle) not verified at parse time.
• R2 simplification across compose() boundaries. simplify_ir detects R2 bigons by arc-index overlap, but compose() renumbers arcs so adjacent sigma/sigma_inv pairs are not detected. Tracked in KRLAdapter.jl issues.
• No pretty-printer. KRLProgram → string round-trip not yet implemented.
• No RESOLVE family. classify is parsed and lowered (identity) but not dispatched to the query layer.

Grade E criterion: "At least 1 test, documented failures."

• Grammar drafted: spec/grammar.ebnf, spec/grammar-overview.md
• 4 examples in examples/
• Shell smoke test: tests/smoke/grammar_smoke.sh (16 lexical assertions)

After D: typechecker (port-arity + generator index validity), deeper TangleIR compilation correctness, annotation per-directory, dogfooding by parsing 20+ KRL programs from the knot table. Fix R2 simplification across compose() boundaries.

After C: 6+ diverse external targets (knot researchers, DSL authors, topology educators) write KRL programs and report back.

After D: typechecker (port-arity + generator index validity), compiler to TangleIR via KRLAdapter.jl, deep annotation per-directory, real dogfooding by parsing 20+ KRL programs representing knots from the knot table.

After C: 6+ diverse external targets (knot researchers, DSL authors, topology educators) write KRL programs and report back.

Templated from rsr-template-repo. Zero KRL-specific content.

• spec/grammar.ebnf (v0.1.0 EBNF)
• spec/grammar-overview.md
• 4 examples/ programs
• tests/smoke/grammar_smoke.sh (16 lexical assertions, all passing)

• Decision: Option B — Julia in KRLAdapter.jl
• Implemented: lexer, AST, recursive-descent parser, lowering (KRLAdapter.jl)
• Grammar ambiguity fixed: ; as compose only inside parentheses
• 57 dedicated parser tests + all 4 example files parse cleanly
• 5577 total KRLAdapter.jl tests pass

Reassess on typechecker implementation or when 20+ knot-table programs have been parsed successfully.