BSK-W0040 warning

Lambda function missing type annotations

Emitted when a lambda function is assigned to a variable without type annotations. This is a warning rather than an error since lambda functions are often used for simple operations where type annotations might be considered verbose.

# BAD (warning)
f = lambda x: x + 1  # W: lambda assigned to unannotated variable 'f'

# GOOD
f: Callable[[int], int] = lambda x: x + 1  # OK: variable has type annotation

How to handle it

Every rule is on by default — strict is the default, not a cage. You can dial BSK-W0040 down per-file or per-path from your editor or pyproject.toml, or fix the code so it type-checks. See the Warnings rules and the complete diagnostic reference.

Canonical URL: https://www.basilisk-python.dev/warnings/BSK-W0040