# JOURNAL-lex

## 2026-06-15

### Build

Created `calc/__init__.py` (empty package marker) and `calc/lexer.py` implementing:
- `Token` dataclass with `kind` (str) and `value` (int | float | None)
- `LexError(Exception)` raised on invalid characters with offending char and position
- `tokenize(src: str) -> list[Token]` covering numbers (int/float, leading/trailing dot), operators, parens, whitespace skipping, and error raising
- `EOF` singleton token appended at end of every token list

Created `calc/test_lexer.py` with 18 unittest cases covering D1–D3 including the three mandatory inputs.

### Verification

All four DoD gates observed passing:
- D1: integers, floats (3.14, .5, 10.) tokenize correctly with right Python type
- D2: all six operator/paren kinds correct; `1+2*3` yields expected sequence
- D3: whitespace skipped; `@` raises LexError with position 2 in message
- D4: 18 tests, 0 failures

Commit: 70b71caacd1f7334e387ff15b007573201b524b6