Data commit

Task/Determine-if-a-string-is-collapsible/Haskell/determine-if-a-string-is-collapsible-1.hs

@@ -0,0 +1,22 @@
+import Text.Printf (printf)
+import Data.Maybe (catMaybes)
+import Control.Monad (guard)
+
+input :: [String]
+input = [ ""
+        , "The better the 4-wheel drive, the further you'll be from help when ya get stuck!"
+        , "headmistressship"
+        , "\"If I were two-faced, would I be wearing this one?\" --- Abraham Lincoln "
+        , "..1111111111111111111111111111111111111111111111111111111111111117777888"
+        , "I never give 'em hell, I just tell the truth, and they think it's hell. "
+        , "                                                    --- Harry S Truman  "
+        , "😍😀🙌💃😍😍😍🙌"
+        ]
+
+collapse :: Eq a => [a] -> [a]
+collapse = catMaybes . (\xs -> zipWith (\a b -> guard (a /= b) >> a) (Nothing : xs) (xs <> [Nothing])) . map Just
+
+main :: IO ()
+main =
+  mapM_ (\(a, b) -> printf "old: %3d «««%s»»»\nnew: %3d «««%s»»»\n\n" (length a) a (length b) b)
+  $ ((,) <*> collapse) <$> input

Task/Determine-if-a-string-is-collapsible/Haskell/determine-if-a-string-is-collapsible-2.hs

@@ -0,0 +1,7 @@
+import Data.List (group)
+
+isCollapsible :: String -> Bool
+isCollapsible = any ((1 <) . length) . group
+
+collapsed :: String -> String
+collapsed = map head . group

Task/Determine-if-a-string-is-collapsible/Haskell/determine-if-a-string-is-collapsible-3.hs

@@ -0,0 +1,11 @@
+isCollapsible :: String -> Bool
+isCollapsible [] = False
+isCollapsible [_] = False
+isCollapsible (h:t@(x:_)) = h == x || isCollapsible t
+
+collapsed :: String -> String
+collapsed [] = []
+collapsed [x] = [x]
+collapsed (h:t@(x:_))
+  | h == x = collapsed t
+  | otherwise = h : collapsed t