[eyadstein]

Closes #37

What changed

• Lexer: the operator pattern now also matches +=, -=, *=, /=, %=, &=, |= and ^=.
• AST: new CompoundAssign and ArrayCompoundAssign nodes.
• Parser: recognized in statements, for initializers and for steps (for example i += 2).
• Code generation: a op= e is lowered to a = a op e through the existing BinaryOp code, so every operator behaves exactly like its expanded form. For arrays, the index is evaluated once into a hidden variable, so arr[f()] += 1 does not call f() twice. This uses one extra byte of RAM per array compound assignment statement.

Not included

<<= and >>= are left out: the compiler has no << or >> operators yet, so they would need that feature first. Happy to follow up if you want shifts added.

How I tested

• Five new tests in tests/test_compiler.py: all eight operators on scalars, a compound right-hand side (a += b * 2), a for loop step, array elements, and an array index with a side effect that must run exactly once.
• uv run pytest: 281 passed (276 before this change plus the 5 new ones).
• ruff check and ruff format --check on src and tests: clean.
• Run locally on Windows with Python 3.13 only. The 3.11 and 3.12 jobs in CI are the check for the other versions.

[sql-hkr]

LGTM! Excellent implementation. Resolved the minor conflict with #41. Thank you for the contribution!

[codecov]

Codecov Report

❌ Patch coverage is 88.09524% with 5 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/tiny8/compiler.py	88.09%	5 Missing ⚠️

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