Initial data commit

Task/Substring-Top-and-tail/Haskell/substring-top-and-tail-1.hs

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+-- We define the functions to return an empty string if the argument is too
+-- short for the particular operation.
+
+remFirst, remLast, remBoth :: String -> String
+
+remFirst "" = ""
+remFirst cs = tail cs
+
+remLast "" = ""
+remLast cs = init cs
+
+remBoth (c:cs) = remLast cs
+remBoth  _     = ""
+
+main :: IO ()
+main = do
+  let s = "Some string."
+  mapM_ (\f -> putStrLn . f $ s) [remFirst, remLast, remBoth]

Task/Substring-Top-and-tail/Haskell/substring-top-and-tail-2.hs

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+word = "knights"
+
+main = do
+    -- You can drop the first item
+    -- using `tail`
+    putStrLn (tail word)
+
+    -- The `init` function will drop
+    -- the last item
+    putStrLn (init word)
+
+    -- We can combine these two to drop
+    -- the last and the first characters
+    putStrLn (middle word)
+
+-- You can combine functions using `.`,
+-- which is pronounced "compose" or "of"
+middle = init . tail

Task/Substring-Top-and-tail/Haskell/substring-top-and-tail-3.hs

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+main :: IO ()
+main = mapM_ print $ [tail, init, init . tail] <*> ["knights"]