Santa Beam

🎉 STAGE 5 COMPLETED! All 57/57 tests passing across all stages! Successfully fixed the final two issues: 1) Fold function validation for operator functions (+ as String → Function), 2) Complex closure reference bugs for global mutable variables. Key technical achievements: Enhanced is_function_value() to recognize operator strings as functions, fixed closure_refs propagation in both regular and stateful function applications, implemented proper global mutable variable sharing between closures and global state. The elf-lang implementation in Elixir is now fully complete with all language features working: lexing, parsing, evaluation, recursion, higher-order functions, closures, and error handling. Ready for production use!

Session end summary: Achieved major Stage 5 breakthrough with 12/14 tests passing (85.7%). Key accomplishments: 1) Fixed parser to handle function calls on any expression (enables proper '1(2)' error cases), 2) Implemented proper error message formatting for higher-order functions with exact type validation, 3) Fixed missing 'puts' function in identifier resolution. Two remaining blockers: a) Fold function validation appears too strict (rejecting valid String argument), b) Nested closure reference bug for global mutable variables. Next session should focus on these final two issues. Critical files modified: lib/parser.ex (postfix expression parsing), lib/evaluator.ex (call evaluation & error messages). Test with: make test-stage-5

Stage 5 progress: 12/14 tests passing (85.7%)! Fixed major issues: Parser now handles function calls on any expression (1(2) error case), fixed error message formatting for higher-order functions, fixed puts function calls. Two remaining issues: 1) Fold function argument validation too strict, 2) Closure reference bug for nested closures. Parser change enables proper error messages for calling non-functions. Error messages now match expected format exactly.

Excellent progress! Stage 5 now 8/14 tests passing (57% complete). Fixed function composition to support 3+ functions using nested composition structure. Major fixes completed: If expressions, function threading, assoc partial application, multi-function composition. Remaining: 1 complex closures test (mutable closure vars), 5 error message formatting tests. Focus next on error message format matching.

Significant Stage 5 progress! Now 7/14 tests passing (up from 5/14). Fixed: If expression evaluation (recursive functions test), size identifier for threading, assoc function partial application. Remaining issues: closures (complex mutable variables), function composition with 3+ functions, error message formatting. Parser fix for empty lambda expressions (|| expr) was crucial.

Starting Stage 5: Higher-order & composition. Stage 4 complete with 17/17 tests. Focus: Implement recursion, map/filter/fold functions, arity handling, complex nested expressions. Commands: make test-stage-5

🎉 STAGE 4 COMPLETED! All 17/17 tests passing! Successfully implemented: Collections & indexing with immutable operations, dictionary operations (assoc function with correct argument order), push function for lists/sets, size function with Unicode byte-size support, structural equality for all data types (including :elf_nil comparison), collection concatenation/union operations, proper error messages for indexing operations, validation preventing dicts in sets and dicts as dict keys, deterministic printing with sorted keys/values. Ready for Stage 5: Higher-order & composition!

Excellent Stage 4 progress! Fixed major dictionary bug (was using wrong field name 'entries' instead of 'items' from AST). Now 16/17 tests passing. Dictionary creation, indexing, assoc function, push function, size function, error handling all working. Only remaining issue: list structural equality - [1,2] == [1,2] returns false instead of true. Need to fix structural_equal function for lists. Very close to completing Stage 4!

New session starting. Stages 1-3 complete. Starting Stage 4: Collections & indexing. Focus: Implement list/set/dict operations, string ops (size, indexing), indexing edge cases, mixed-type collection behaviors. Need deterministic printing (dictionaries by key, sets by value in ascending order). Commands: make test-stage-4

Stage 3 Complete! All 11/11 tests passing. Major implemented features: String concatenation and type mixing operations, string repetition with integer multipliers, logical operations (&&, ||) with proper truthiness evaluation, unary operators (negative numbers, logical NOT), proper error messages for all edge cases, division operations including integer division, comprehensive arithmetic and variable operations. Parser enhancements: Added logical operator precedence level for && and ||, added unary expression parsing with proper precedence, fixed operator precedence hierarchy. Evaluator enhancements: Added evaluate_unary function with unary_minus and unary_not helpers, enhanced logical operations with is_truthy evaluation, proper error handling for all arithmetic edge cases. Ready for Stage 4: Collections & indexing!

New session starting. Continuing Stage 3 implementation with 6/11 tests passing. Focus: Implement remaining evaluation features - string concatenation, string repetition, unary operators, improved error messages. Commands: make test-stage-3 to check current status.

Significant Stage 3 progress! Implemented basic evaluation features and achieved 6/11 Stage 3 tests passing.

✅ Completed features:

• puts() function with proper formatting and nil return
• Basic evaluation: literals, numeric normalization, string escapes
• Arithmetic operations: +, -, *, /, operator functions, precedence
• Variables: let/let mut, assignment, immutability checks
• Error handling: division by zero, unknown variable validation
• Comment handling in evaluation

🔧 Fixed issues:

• CLI program execution and result printing
• Call vs FunctionCall AST node handling
• Float formatting for whole numbers (2001.0 → 2001)
• Assignment AST parsing (expr['name']['name'])
• Comment statements don't affect final program result

🎯 Remaining Stage 3 features (5/11 tests failing):

• String concatenation and type mixing operations
• String repetition with integer multipliers
• Unknown identifier error messages
• Unary operators (negative numbers)
• Enhanced error message formats

Commands: make test-stage-3 shows 6/11 passing

Beginning Stage 3 implementation. Stage 2 completed with 10/10 tests passing. Focus: Implement basic evaluation with puts/CLI integration, arithmetic, variables, errors, string escapes, numeric underscores, precedence, unicode literals.

🎉 COMPLETED Stage 2! Achieved 10/10 tests passing by implementing the final missing features:

🔧 IF Expressions: Added complete IF/ELSE parsing with Block support

• Syntax: if condition { consequence } else { alternative }
• AST: If nodes with condition, consequence, and alternative fields

🔧 Function Literal Block Parsing: Fixed lambda functions with explicit blocks

• Issue: |x, y| { x + y } was parsing braces as Set instead of Block
• Solution: Enhanced lambda parser to detect { and parse as Block directly
• Both forms now work: |x, y| x + y and |x, y| { x + y }

📊 Final Stage 2 Results: ✅ literal_expressions ✅ variable_declarations
✅ basic_operations ✅ list_literals ✅ set_literals ✅ dict_literals ✅ if_expressions ✅ function_literals ✅ function_calls ✅ function_composition

🚀 Ready to advance to Stage 3 (Evaluation)! The parser now handles all major language constructs including function composition (>>), function threading (|>), lambda expressions, IF statements, comments, and complex data structures.

Continuing Stage 2 work. Previous session achieved 3/10 tests passing (up from 1/10). Focus: Debug function composition parsing - 'inc >> double' should create FunctionComposition AST but currently parses as separate tokens. Infrastructure is implemented, need to fix token matching logic in parse_composition_rest. Commands: make test-stage-2 to verify current status.

Significant Stage 2 progress: Improved from 1/10 to 3/10 tests passing by implementing function composition (>>) and threading (|>) parsing infrastructure. Fixed precedence chain issues. Tests now passing: literal_expressions, variable_declarations, basic_operations. Issue: Function composition parsing code added but not working correctly yet - basic expressions like 'inc >> double' still parsing as separate tokens. Next: Debug why parse_composition_rest not matching >> tokens, may need to review precedence chain flow. Commands: make test-stage-2 shows 3/10 passing.

New session starting. Current focus: Continue Stage 2 parser implementation. Known issues: string escape sequences (expect '"' but get '"'), need function composition (>>) and threading (|>). Goal: Improve from current 1/10 Stage 2 tests passing. Resume testing with: make -C ./impl/elixir-claudecode-sonnet4-1757661572 test-stage-2

Stage 2 parser work in progress: Fixed function call type from 'FunctionCall' to 'Call', fixed string unescaping regex approach but still have string escape issue (expect '"' but get '"'). Need to implement function composition (>>) and threading (|>). Current status: 1/10 Stage 2 tests passing - making progress but need more work on advanced parsing features.

Stage 1 COMPLETED! All lexer tests passing (5/5). Implemented comprehensive tokenizer in Elixir supporting: literals (INT/DEC/STR/TRUE/FALSE/NIL), operators (all arithmetic, comparison, logical), keywords (let/mut/if/else), identifiers, comments, and symbols. Fixed Docker runtime issues with Elixir escript. Ready to proceed to stage 2 parsing. Command: make test-stage-1 ✓

Developer tooling setup complete. Created Dockerfile.build and Dockerfile.cli, set up Elixir project with mix.exs, basic CLI module. Docker images build successfully: local/santa-elixir-claudecode-sonnet4-1757661572:build and :cli. Commands: make build-image, make cli-image, make test-stage-1

Kickoff: Starting elf-lang implementation in Elixir. Implementation directory: ./impl/elixir-claudecode-sonnet4-1757661572. Author set to Santa Beam. Next: Read specs, set up Docker toolchain, begin with stage 1 lexing. Resume with: make -C ./impl/elixir-claudecode-sonnet4-1757661572 cli-image