Ruby Rednose

🎉 IMPLEMENTATION COMPLETE! All 57/57 tests passing across all stages 1-5. Successfully fixed the final two issues in Stage 5: 1) Closures now properly capture mutable variables by reference using shared VariableCell objects, and assignment expressions return their assigned values, 2) Fixed program evaluation logic to ignore trailing comments when determining final result. The elf-lang Ruby implementation is fully functional with comprehensive lexing, parsing, evaluation, closures, higher-order functions, partial application, function composition, threading, and error handling. Ready for production use.

Stage 5 progress: 12/14 tests passing. Successfully implemented: partial application, higher-order functions (map/filter/fold), function composition (>>), pipeline threading (|>), recursive functions, and all error handling. Remaining issues: 1) Closures not properly capturing mutable variables by reference - assignment in closures doesn't affect captured vars, 2) assoc partial application with threading has argument count issue. Core functionality complete, working on final two edge cases.

Stage 4 COMPLETE! All 17 collection and indexing tests now passing. Implemented: immutable collections (List, Set, Dictionary), built-in functions (push, assoc, first, rest, size), collection operations (+), indexing for strings/lists/dictionaries, structural equality, error handling for type mismatches, and deterministic printing with proper sorting. Key features: push/assoc return new collections, proper Unicode byte-size counting, negative indexing, Set deduplication, right-biased dictionary merging. All stages 1-4 passing. Ready for Stage 5 - Higher-order & composition.

Starting Stage 4 - Collections & indexing. Key requirements: immutable operations (push, assoc), built-ins (first, rest, size), indexing for strings/lists/dicts, structural equality, collection merging. Focus on maintaining existing functionality while adding new features.

Stage 3 COMPLETE! All 11 evaluation tests passing. Implemented full evaluator with environment, variables (let/let mut), assignment, arithmetic operations, puts function, operator functions (+, -, *, /), type mixing, string operations, error handling, and proper integer division (truncate toward zero). All stages 1-3 now passing. Ready to advance to Stage 4 - Collections & indexing.

Stage 2 COMPLETE! All parsing tests now passing (10/10). Fixed AST structure issues: Set/Dictionary 'items' field, Index 'left' field, If expression 'consequence'/'alternative' fields, Function literals always wrapped in Block, and special handling for FunctionComposition (>>) and FunctionThread (|>) operators with flattened arrays. Parser now correctly handles all Stage 2 features: literals, variable declarations, arithmetic with precedence, collections (lists/sets/dicts), indexing, if-expressions, function literals, function calls, and composition. Ready to advance to Stage 3 - Basic evaluation.

Stage 1 COMPLETE! All lexing tests passing. Implemented comprehensive Ruby lexer supporting integers, decimals with underscores, strings with UTF-8 and escapes, booleans, nil, operators, keywords, identifiers, and comments. Fixed comment tokenization bug by properly handling newline characters. Next step: Stage 2 parsing.

Developer tooling setup complete. Built local/santa-ruby-claudecode-sonnet4-1757425857:build and :cli images successfully. Commands used: make build-image, make cli-image. CLI is ready for testing.

Starting elf-lang Ruby implementation as author 'Ruby Rednose'. Initial focus: set up Dockerized toolchain and begin Stage 1 lexing. Resume command: make -C ./impl/ruby-claudecode-sonnet4-1757425857 cli-image