Add remaining haskell book exercises

Haskell-book/14/morse/tests/CoArbitrary.hs

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+{-# LANGUAGE DeriveGeneric #-}
+
+module CoArbitrary where
+
+import GHC.Generics
+import Test.QuickCheck
+
+data Bool' = True' | False' deriving (Generic)
+
+instance CoArbitrary Bool'
+
+trueGen :: Gen Int
+trueGen = coarbitrary True' arbitrary
+
+falseGen :: Gen Int
+falseGen = coarbitrary False' arbitrary

Haskell-book/14/morse/tests/WordNumberTest.hs

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+module Main where
+
+import Test.Hspec
+import WordNumber (digitToWord, digits, wordNumber)
+
+main :: IO ()
+main = hspec $ do
+    describe "digitToWord" $ do
+        it "returns zero for 0" $ do
+            digitToWord 0 `shouldBe`"zero"
+        it "returns one for 1" $ do
+            digitToWord 1 `shouldBe` "one"
+
+    describe "digits" $ do
+        it "returns [1] for 1" $ do
+            digits 1 `shouldBe` [1]
+        it "returns [1, 0, 0] for 100" $ do
+            digits 100 `shouldBe` [1, 0, 0]
+
+    describe "wordNumber" $ do
+        it "one-zero-zero given 100" $ do
+            wordNumber 100 `shouldBe` "one-zero-zero"
+        it "nine-zero-zero-one for 9001" $ do
+            wordNumber 9001 `shouldBe` "nine-zero-zero-one"

Haskell-book/14/morse/tests/tests.hs

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+module Main where
+
+import qualified Data.Map as M
+import Morse
+import Test.QuickCheck
+import Test.QuickCheck.Gen (oneof)
+
+allowedChars :: [Char]
+allowedChars = M.keys letterToMorse
+
+allowedMorse :: [Morse]
+allowedMorse = M.elems letterToMorse
+
+charGen :: Gen Char
+charGen = elements allowedChars
+
+morseGen :: Gen Morse
+morseGen = elements allowedMorse
+
+prop_thereAndBackAgain :: Property
+prop_thereAndBackAgain =
+    forAll charGen (\c -> ((charToMorse c) >>= morseToChar) == Just c)
+
+main' :: IO ()
+main' = quickCheck prop_thereAndBackAgain
+
+data Trivial = Trivial deriving (Eq, Show)
+
+trivialGen :: Gen Trivial
+trivialGen = return Trivial
+
+instance Arbitrary Trivial where
+    arbitrary = trivialGen
+
+main :: IO ()
+main = do
+    sample trivialGen
+
+data Identity a = Identity a deriving (Eq, Show)
+
+identityGen :: Arbitrary a => Gen (Identity a)
+identityGen = do
+    a <- arbitrary
+    return (Identity a)
+
+instance Arbitrary a => Arbitrary (Identity a) where
+    arbitrary = identityGen
+
+identityGenInt :: Gen (Identity Int)
+identityGenInt = identityGen
+
+data Pair a b = Pair a b deriving (Eq, Show)
+
+pairGen :: (Arbitrary a, Arbitrary b) => Gen (Pair a b)
+pairGen = do
+    a <- arbitrary
+    b <- arbitrary
+    return (Pair a b)
+
+instance (Arbitrary a, Arbitrary b) => Arbitrary (Pair a b) where
+    arbitrary = pairGen
+
+pairGenIntString :: Gen (Pair Int String)
+pairGenIntString = pairGen
+
+data Sum a b = First a | Second b deriving (Eq, Show)
+
+sumGenEqual :: Gen (Sum Char Int)
+sumGenEqual = do
+    a <- arbitrary
+    b <- arbitrary
+    oneof [return $ First a,
+           return $ Second b]
+
+sumGenCharInt :: Gen (Sum Char Int)
+sumGenCharInt = sumGenEqual
+
+sumGenFirstPls :: (Arbitrary a, Arbitrary b) => Gen (Sum a b)
+sumGenFirstPls = do
+    a <- arbitrary
+    b <- arbitrary
+    frequency [(10, return $ First a),
+               (1, return $ Second b)]
+
+sumGenCharIntFirst :: Gen (Sum Char Int)
+sumGenCharIntFirst = sumGenFirstPls