--------------------
-- Some sample solutions for the titling problem from Lab 2


--------------------
-- 3 approaches of increasing efficiency,
-- plus two (bad) attempts at explicit definition

-- (It's worth noting that the results of "words xs" 
-- is always a list of non-empty Strings, so that
-- the cap functions in versions 1-3 are sufficient)

title1 = unwords . map cap . words . map toLower
         where cap (x:xs) = toUpper x : xs
         
title2 = unwords . map (cap . map toLower) . words
         where cap (x:xs) = toUpper x : xs
         
title3 = unwords . map cap . words
         where cap (x:xs) = toUpper x : map toLower xs

-- these versions try to be more efficient by making only
-- one pass on the data ... but they actually run slower!

title4 = tf True where
                 tf _ [] = []
                 tf True  (x:xs) | isSpace x =       tf True xs
                 tf False (x:xs) | isSpace x = ' ' : tf True xs
                 tf True  (x:xs) | isAlpha x = toUpper x : tf False xs
                 tf False (x:xs) | isAlpha x = toLower x : tf False xs
                 tf _     (x:xs) | otherwise =         x : tf False xs

title5 = tt where
         tt [] = []
         tt (x:xs) | isAlpha x = toUpper x : tf xs
                   | isSpace x =     tt xs
                   | otherwise = x : tf xs
         tf [] = []
         tf (x:xs) | isAlpha x = toLower x : tf xs
                   | isSpace x = ' ' : tt xs
                   | otherwise = x : tf xs

-- some sample strings

texts = [ "This is a SAMPLE title for You!",
          "Here's  one   with     LOTSA   Spaces",
          "Short Title" ]

-- try "test titleN" for N <- [1..5]

test = flip map texts