Solved: remove consecutive duplicates

Firstly, understanding the problem is utmost important. Consecutive duplicates in a list occur when the same data point occurs in two or more places in the array, but only if these duplications occur in a row. For example, in the list [1, 2, 2, 3, 2], the ‘2’ data point is duplicated, but it is not considered a consecutive duplication because it is not in a row with the first ‘2’. However, the list [1, 2, 2, 3] does contain a pair of consecutive ‘2’s.

For this issue, Haskell presents a highly flexible, well-optimized solution with its built-in library functions. Particularly, the ‘group’ function from the `Data.List` library would be utilized.

import Data.List (group)

removeDuplicates :: Eq a => [a] -> [a]
removeDuplicates = map head . group

This short, succinct code snippet eliminates consecutive duplicates by dividing the original list into sub-lists of duplicate elements (group), then replacing each sub-list with the first element (map head).

Understanding the removeDuplicates function

To gain a better understanding of how the code works, let’s break it down.

Importing the necessary library: The code begins with `import Data.List (group)`. Here, we’re importing the ‘group’ function from the ‘Data.List’ library. ‘group’ is a very handy function in Haskell that splits a list into sub-lists of identical, contiguous elements.

Defining the function: We then move to `removeDuplicates :: Eq a => [a] -> [a]`. This is the type declaration for our function. It simply states that our function takes a list of any data type ‘a’ (where ‘a’ is a member of the class ‘Eq’, or can be checked for equality), and will return a list of the same data type.

Detailed Explanation of Steps

Now, focusing on the part of `removeDuplicates = map head . group`, it is the definition of our function which averages the beauty of Haskell’s functional programming features.

Function composition: The expression uses the ‘.’ operator which in Haskell, means function composition. Basically we’re creating a new function by combining ‘group’ and ‘map head’.

‘group’ function: The function ‘group’ takes our input list and breaks it down into sub-lists where all the identical, contiguous elements are grouped together.

‘map head’ function: Then ‘map head’ goes ahead and replaces each sub-list with the first element of that sub-list – effectively removing all the consecutive duplicates. It’s done in a very efficient way and is readable as well.

This code illustrate how we can effectively use Haskell’s rich library functions and functional programming features to do a lot with a little.

Haskell Libraries and Functions

The greatness of Haskell lies in its library support and in-built functions. Haskell’s Data.List library is a treasure trove of useful functions for list processing, ‘group’ being one amongst them. Another function, ‘nub’, can also be employed to remove all duplicates irrespective of their position.

The rich set of libraries and the strongly typed, functional programming approach makes Haskell a highly flexible and reliable language for tackling real-world problems. Besides, the easy-to-understand syntax makes code debugging and comprehension quite straightforward.

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