listfilterlambda

Listfilterlambda is a term used to describe the pattern of filtering a list by applying a predicate defined as a lambda function. This approach relies on first-class functions and a higher-order filtering operation, commonly appearing in functional-style programming in languages such as Python and JavaScript. The lambda provides a compact, unnamed condition that determines which elements of the list are kept.

In Python, a typical form uses the filter function with a lambda predicate. For example, given a list of numbers, one may extract even values with a lambda that returns true for even elements: lst = [1, 2, 3, 4, 5]; evens = list(filter(lambda x: x % 2 == 0, lst)). Note that in Python 3, filter returns an iterator, so list() converts it to a list. In JavaScript, the equivalent pattern uses the Array.prototype.filter method with an arrow function: const arr = [1, 2, 3, 4, 5]; const evens = arr.filter(x => x % 2 === 0).

While the listfilterlambda pattern can be concise, it can reduce readability for complex conditions. In Python, list comprehensions offer an arguably clearer alternative that achieves the same result with the same expressive power: [x for x in lst if x % 2 == 0]. Developers should weigh brevity against clarity and consider readability, maintainability, and performance when choosing between lambda-based filtering and alternative constructs.

See also: list comprehension, filter, lambda expression, functional programming.