Step by Step solution about How to resolve the algorithm Comma quibbling step by step in the Haskell programming language

First implementation

The first implementation of the quibble function uses pattern matching to handle different cases of the input list ws:

• If the list is empty, it returns an empty string.
• If the list contains only one element, it returns that element.
• If the list contains two elements, it joins them with "and".
• If the list contains more than two elements, it joins the first element with ", " and recursively calls quibbles on the remaining elements.

The main function applies the quibble function to several lists of strings and prints the results to the console.

DetailedExplanation

The first implementation uses pattern matching to handle different cases of the input list ws:

• If the list is empty, it returns an empty string.
• If the list contains only one element, it returns that element.
• If the list contains two elements, it joins them with "and".
• If the list contains more than two elements, it joins the first element with ", " and recursively calls quibbles on the remaining elements.

Second implementation

The second implementation of the quibble function uses the intercalate function from the Data.List module to join the elements of the input list with the specified separator.

• If the input list contains more than one element, it splits the list into two parts: the head (first element) and the tail (remaining elements). It then reverses the tail, joins the elements with ", ", and reverses the result. Finally, it joins the head and tail with " and ".
• If the input list contains only one element, it returns that element as a string.

The main function applies the quibble function to several lists of strings and prints the results to the console.

Detailed Explanation

The second implementation uses the intercalate function from the Data.List module to join the elements of the input list with the specified separator.

• If the input list contains more than one element, it splits the list into two parts: the head (first element) and the tail (remaining elements). It then reverses the tail, joins the elements with ", ", and reverses the result. Finally, it joins the head and tail with " and ".
• If the input list contains only one element, it returns that element as a string.

Comparison

The second implementation is more concise and readable than the first implementation. It also uses a more efficient algorithm for joining the elements of the input list.

quibble ws = "{" ++ quibbles ws ++ "}"
  where quibbles [] = ""
        quibbles [a] = a
        quibbles [a,b] = a ++ " and " ++ b
        quibbles (a:bs) = a ++ ", " ++ quibbles bs

main = mapM_ (putStrLn . quibble) $
  [[], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]] ++ 
  (map words ["One two three four", "Me myself I", "Jack Jill", "Loner" ])


import Data.List (intercalate)

--------------------- COMMA QUIBBLING --------------------

quibble :: [String] -> String
quibble ws@(_ : _ : _) =
  intercalate
    " and "
    ( [intercalate ", " . reverse . tail, head]
        <*> [reverse ws]
    )
quibble xs = concat xs

--------------------------- TEST -------------------------
main :: IO ()
main =
  mapM_ (putStrLn . (`intercalate` ["{", "}"]) . quibble) $
    [[], ["ABC"], ["ABC", "DEF"], ["ABC", "DEF", "G", "H"]]
      <> ( words
             <$> [ "One two three four",
                   "Me myself I",
                   "Jack Jill",
                   "Loner"
                 ]
         )