subsequence-repetition: document

subsequence-repetition/SubsequenceRepetition.hs

@@ -1,3 +1,4 @@
+-- | Module to find and print all repetitions of substrings in a given string.
 module Main where
 
 import Control.Monad (forM_)
@@ -6,6 +7,7 @@ import Data.List (sortOn)
 import Data.Map qualified as Map
 import Data.Set qualified as Set
 
+-- | Creates a sliding window of a given size over a list.
 slidingWindow :: Int -> [a] -> [[a]]
 slidingWindow size list
   | size > 0 && length list >= size =
@@ -29,6 +31,7 @@ pairwiseComparison xs = [(x1, i, j) | (i, x1) <- ixs, (j, x2) <- ixs, x1 == x2,
 allPairwiseComparisons :: (Eq a) => [a] -> [[([a], Int, Int)]]
 allPairwiseComparisons xs = map (\n -> pairwiseComparison (slidingWindow n xs)) [0 .. length xs]
 
+-- | Finds all repetitions of substrings of a given list.
 allRepetitions :: (Ord a) => [a] -> [Map.Map [a] (Set.Set Int)]
 allRepetitions xs = map (\n -> findRepetitions (slidingWindow n xs)) $ reverse [0 .. length xs]
 
@@ -40,11 +43,15 @@ printAllRepetitions str substrRepetitions = do
       zipWith
         (const $ \x -> if x then '*' else ' ')
         str
-        [i `elem` concatMap (\x -> [x .. x + length key - 1]) (Set.toList value) | i <- [0 ..]]
+        (isInRange (length key) (Set.toList value))
     putStrLn $ "\t" ++ show key
   where
     score (substring, occurrences) = negate $ length substring ^ 2 * Set.size occurrences
+    isInRange len indices = [i `elem` concatMap (\x -> [x .. x + len - 1]) indices | i <- [0 ..]]
 
+-- | Prints a pairwise comparison of the substrings in a grid format.
+-- The grid will have 'x' for matching pairs and '_' for non-matching pairs.
+-- The first row and column will show the indices of the substrings.
 printPairwiseComparison :: [(Int, Int)] -> IO ()
 printPairwiseComparison [] = return ()
 printPairwiseComparison xys =
@@ -64,6 +71,7 @@ printPairwiseComparison xys =
           putChar '\n'
         putChar '\n'
 
+main :: IO ()
 main = do
   let str = map toLower $ (" " ++) $ "nachts im dichten fichtendickicht da sind dicke fichten wichtig"
   printAllRepetitions str (allRepetitions str)