* * *Both sections relate to the case study: Index for a document of text.* * * *SECTION A: * * * *Given the attached Haskell code which produces an index of words, make the following alterations by modifying existing functions and including new functions where necessary – parts 1) to 5):* * * *1) **Where a word occurs N times on the same line, ensure that the line number occurs n times in the index entry for that word. * * * *2) **Allow words to be hyphenated and treat a hyphenated word as a single word. However, for those words which are split over two lines, treat a split word as a single word without the hyphen. * * * *3) **Treat a capitalised word (one or more capitals) as being different from the word in all lower case (but they should still be sorted alphabetically) – unless it is at the start of a sentence with only the initial letter capitalised. A sentence is terminated by a ‘.’, ‘?’ or ‘!’. * * * *4) **Make the output more readable in the form of an index table in columns with appropriate spacing and without brackets. * * * *5) **Include a user-friendly menu, so that the user can choose input/output file names or default files, and choose to rerun or exit. * * * *Parts 1) to 5) may be developed in any order. * * * * * *SECTION B:* * * *6) **For your version of function, makeIndex (only), show how an alternative ordering of the composed functions would provide a more efficient execution of makeIndex. Justify your answer. * * * *7) **For the parts 1) to 5) above that you have attempted, discuss the use you have made of a) higher-order functions, b) list comprehension, c) monadic input/output, d) functional composition, and/or e) partial parameterisation (or Curried functions). Include an evaluation of how useful your use of these concepts has been. * * * *------------------------------------------------------------------- * * * *import Prelude* * * *type Doc = String* *type Line = String* *type Word = String * * * *makeIndex :: Doc -> [ ([Int], Word) ]* * * *makeIndex* * = shorten . -- [([Int], Word)] -> [([Int], Word)]* * amalgamate .-- [([Int], Word)] -> [([Int], Word)]* * makeLists . -- [(Int, Word)] -> [([Int], Word)]* * sortLs . -- [(Int, Word)] -> [(Int, Word)]* * allNumWords .-- [(Int, Line)] -> [(Int, Word)]* * numLines . -- [Line] -> [(Int, Line)]* * splitUp -- Doc -> [Line]* * * *splitUp :: Doc -> [Line]* * * *splitUp [] = []* *splitUp text* * = takeWhile (/='\n') text : -- first line* * (splitUp . -- splitup other lines* * dropWhile (==’\n’) . -- delete 1st newline(s)* * dropWhile (/='\n')) text -- other lines* * * *numLines :: [Line] -> [(Int, Line)]* * * *numLines lines -- list of pairs of * * = zip [1 .. length lines] lines -- line no. & line* * * *-- for each line* *-- a) split into words* *-- b) attach line no. to each word* * * *splitWords :: Line -> [Word] -- a)* * * *splitWords [] = []* *splitWords line * * = takeWhile isLetter line : -- first word in line* * (splitWords . -- split other words* * dropWhile (not.isLetter) . -- delete separators* * dropWhile isLetter) line -- other words* * where* * isLetter ch* * = (‘a’<=ch) && (ch<=’z’)* * || (‘A’<=ch) && (ch<=’Z’)* * * *numWords :: (Int, Line) -> [(Int, Word)] -- b)* * * *numWords (number, line)* * = map addLineNum ( splitWords line) -- all line pairs* * where* * addLineNum word = (number, word) -- a pair* * * *allNumWords :: [(Int, Line)] -> [(Int, Word)]* * * *allNumWords = concat . map numWords -- doc pairs * * * *sortLs :: [(Int, Word)] -> [(Int, Word)]* * * *sortLs [ ] = [ ]* *sortLs (a:x)* * = sortLs [b | b <- x, compare b a] -- sort 1st half* * ++ [a] ++ -- 1st in middle* * sortLs [b | b <- x, compare a b] -- sort 2nd half* * where* * compare (n1, w1) (n2, w2)* * = (w1 < w2) -- 1st word less* * || (w1 == w2 && n1 < n2) -- check no. * * * *makeLists :: [(Int, Word)] -> [([Int], Word)]* * * *makeLists * * = map mk -- all pairs* * where mk (num, word) = ([num], word)* * -- list of single no.* * * *amalgamate :: [([Int], Word)] -> [([Int], Word)]* * * *amalgamate [ ] = [ ]* *amalgamate [a] = [a]* *amalgamate ((n1, w1) : (n2, w2) : rest)-- pairs of pairs* * | w1 /= w2 = (n1, w1) : amalgamate ((n2, w2) : rest)* * | otherwise = amalgamate ((n1 ++ n2, w1) : rest)* * -- if words are same grow list of numbers* * * *shorten :: [([Int], Word)] -> [([Int], Word)]* * * *shorten* * = filter long -- keep pairs >4* * where* * long (num, word) = length word > 4 -- check word >4* * *