What are the common operations performed on lists in functional languages?

Common operations performed on lists in functional languages include creation, concatenation, mapping, filtering, and reduction.

In functional programming languages, lists are a fundamental data structure used to store collections of items. The operations performed on these lists are central to the manipulation of data in these languages.

Creation of lists is the most basic operation. This involves defining a list with a set of elements. For example, in Haskell, a list of integers could be created as follows: `let numbers = [1, 2, 3, 4, 5]`.

Concatenation is another common operation, which involves joining two or more lists together to form a new list. In Haskell, the `++` operator is used for concatenation. For example, `let moreNumbers = numbers ++ [6, 7, 8, 9, 10]` would result in a new list `moreNumbers` containing the integers from 1 to 10.

Mapping is a higher-order function that applies a given function to each element of a list, returning a new list with the results. For instance, you could use the `map` function in Haskell to square each number in a list: `let squares = map (^2) numbers`.

Filtering is another higher-order function that creates a new list from the elements of an existing list that satisfy a certain condition. For example, you could filter the `numbers` list to only include even numbers: `let evens = filter even numbers`.

Reduction (also known as folding) is a process that reduces a list to a single value by repeatedly applying a binary function. For example, you could use the `foldl` function in Haskell to sum all the numbers in a list: `let sum = foldl (+) 0 numbers`.

These operations are common to most functional languages, although the specific syntax and function names may vary. They provide powerful tools for manipulating lists and are fundamental to understanding and using functional programming effectively.