Initial data commit

Task/Undefined-values/Haskell/undefined-values-1.hs

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+main = print $ "Incoming error--" ++ undefined
+-- When run in GHC:
+-- "Incoming error--*** Exception: Prelude.undefined

Task/Undefined-values/Haskell/undefined-values-2.hs

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+main = print $ length [undefined, undefined, 1 `div` 0]

Task/Undefined-values/Haskell/undefined-values-3.hs

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+resurrect 0 = error "I'm out of orange smoke!"

Task/Undefined-values/Haskell/undefined-values-4.hs

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+undefined :: a
+undefined = error "Prelude.undefined"

Task/Undefined-values/Haskell/undefined-values-5.hs

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+import Control.Exception (catch, evaluate, ErrorCall)
+import System.IO.Unsafe (unsafePerformIO)
+import Prelude hiding (catch)
+import Control.DeepSeq (NFData, deepseq)
+
+scoopError :: (NFData a) => a -> Either String a
+scoopError x = unsafePerformIO $ catch right left
+  where right = deepseq x $ return $ Right x
+        left e = return $ Left $ show (e :: ErrorCall)
+
+safeHead :: (NFData a) => [a] -> Either String a
+safeHead = scoopError . head
+
+main = do
+  print $ safeHead ([] :: String)
+  print $ safeHead ["str"]