# JOURNAL-parse

## Implementation notes

Grammar chose iterative (not recursive) form for expr and term to ensure left-associativity without
risk of right-fold bugs. Unary uses right-recursive call to handle `--5` naturally.

Empty string: `tokenize("")` returns `[Token('EOF', None)]`. `primary()` sees EOF and raises
ParseError — no special-case needed.

`"1 2"` error: `parse()` checks that after `expr()` the current token is EOF; NUMBER is not EOF, so
ParseError raised cleanly.

`")("` error: `primary()` is called, sees RPAREN (not NUMBER or LPAREN), raises ParseError.