Should I Name My Python Lambdas?

Naming Lambdas in Python

The use of lambda expressions in Python offers a concise syntax for defining anonymous functions. However, some developers may encounter the question of whether it's appropriate to name lambdas, particularly within larger functions.

According to PEP8, a coding standard for Python, naming lambdas is discouraged. The rationale is that lambdas are intended to be anonymous, allowing them to be embedded within expressions. Assigning a name to a lambda defeats this purpose, as it becomes a named function.

In the example provided, the author creates a named lambda called indexer to perform complex indexing on numpy arrays. While this approach reduces code duplication, it's not considered Pythonic due to the naming aspect.

Instead, it's recommended to define a separate function when the functionality provided by the lambda is not needed outside the enclosing function. This allows for a clearer structure, improves readability, and aligns with PEP8 guidelines.

Example:

def fcn_operating_on_arrays(array0, array1):
    def indexer(a0, a1, idx):
        return a0[idx] + a1[idx]

    # Code using `indexer`

    return the_answer

By separating the indexing functionality into a named function, the code becomes more modular and adherent to Pythonic best practices.

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