Add remaining haskell book exercises

Haskell-book/17/ListApplicative/.gitignore

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+.stack-work/
+ListApplicative.cabal
+*~

Haskell-book/17/ListApplicative/Setup.hs

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+import Distribution.Simple
+main = defaultMain

Haskell-book/17/ListApplicative/app/Main.hs

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+module Main where
+
+import List
+
+main :: IO ()
+main = return ()

Haskell-book/17/ListApplicative/package.yaml

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+name:                ListApplicative
+version:             0.1.0.0
+author:              "Eugen Wissner"
+maintainer:          "belka@caraus.de"
+copyright:           "2018 Eugen Wissner"
+
+dependencies:
+- base >= 4.7 && < 5
+- QuickCheck
+- checkers
+
+library:
+  source-dirs: src
+
+executables:
+  ListApplicative-exe:
+    main:                Main.hs
+    source-dirs:         app
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - ListApplicative
+
+tests:
+  ListApplicative-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - ListApplicative

Haskell-book/17/ListApplicative/src/List.hs

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+module List where
+
+import Test.QuickCheck
+import Test.QuickCheck.Checkers
+
+data List a =
+    Nil
+  | Cons a (List a)
+  deriving (Eq, Show)
+
+instance Functor List where
+    fmap _ Nil = Nil
+    fmap f (Cons x y) = Cons (f x) (fmap f y)
+
+instance Applicative List where
+    pure f = Cons f Nil
+    Nil <*> _ = Nil
+    _ <*> Nil = Nil
+    f <*> x = flatMap (\f' -> fmap f' x) f
+
+append :: List a -> List a -> List a
+append Nil ys = ys
+append (Cons x xs) ys = Cons x $ xs `append` ys
+
+fold :: (a -> b -> b) -> b -> List a -> b
+fold _ b Nil = b
+fold f b (Cons h t) = f h (fold f b t)
+
+concat' :: List (List a) -> List a
+concat' = fold append Nil
+
+flatMap :: (a -> List b) -> List a -> List b
+flatMap f as = concat' $ fmap f as
+
+append' :: List a -> a -> List a
+append' acc x = Cons x acc
+
+fromList :: [a] -> List a
+fromList xs = foldl (\l a -> Cons a l) Nil xs
+
+instance Arbitrary a => Arbitrary (List a) where
+    arbitrary = frequency [(1, pure Nil),
+                           (5, Cons <$> arbitrary <*> arbitrary)]
+
+instance Eq a => EqProp (List a) where
+    (=-=) = eq

Haskell-book/17/ListApplicative/src/Validation.hs

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+module Validation where
+
+import Test.QuickCheck (Arbitrary(..), frequency)
+import Test.QuickCheck.Checkers
+
+data Validation e a =
+    Failure e
+  | Success a
+  deriving (Eq, Show)
+
+instance Functor (Validation e) where
+    fmap f (Success x) = Success $ f x
+    fmap f (Failure x) = Failure x
+
+instance Monoid e => Applicative (Validation e) where
+    pure = Success
+    (Failure x) <*> (Success _) = Failure x
+    (Success _) <*> (Failure x) = Failure x
+    (Failure f) <*> (Failure y) = Failure $ mappend f y
+    (Success f) <*> (Success y) = Success $ f y
+
+instance (Arbitrary a, Arbitrary e) => Arbitrary (Validation e a) where
+    arbitrary = frequency [(1, Failure <$> arbitrary),
+                           (5, Success <$> arbitrary)]
+
+instance (Eq a, Eq e) => EqProp (Validation e a) where
+    (=-=) = eq

Haskell-book/17/ListApplicative/src/ZipList.hs

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+module ZipList where
+
+import Control.Applicative
+import List
+import Test.QuickCheck
+import Test.QuickCheck.Checkers
+
+take' :: Int -> List a -> List a
+take' _ Nil = Nil
+take' 0 _ = Nil
+take' n (Cons x xs) = Cons x $ take' (n - 1) xs
+
+newtype ZipList' a =
+    ZipList' (List a)
+    deriving (Eq, Show)
+
+instance Eq a => EqProp (ZipList' a) where
+    xs =-= ys = xs' `eq` ys'
+        where xs' = let (ZipList' l) = xs
+                     in take' 3000 l
+              ys' = let (ZipList' l) = ys
+                     in take' 3000 l
+
+instance Functor ZipList' where
+    fmap f (ZipList' xs) = ZipList' $ fmap f xs
+
+instance Monoid a => Monoid (ZipList' a) where
+    mempty = pure mempty
+    mappend = liftA2 mappend
+
+instance Applicative ZipList' where
+    pure f = ZipList' $ repeat
+        where repeat = Cons f repeat 
+    (ZipList' fs) <*> (ZipList' xs) = ZipList' $ applicative fs xs
+        where applicative Nil _ = Nil
+              applicative _ Nil = Nil
+              applicative (Cons f fs) (Cons x xs) = Cons (f x) $ applicative fs xs
+
+instance Arbitrary a => Arbitrary (ZipList' a) where
+    arbitrary = ZipList' <$> arbitrary

Haskell-book/17/ListApplicative/stack.yaml

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+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+# resolver: ghcjs-0.1.0_ghc-7.10.2
+# resolver:
+#  name: custom-snapshot
+#  location: "./custom-snapshot.yaml"
+resolver: lts-10.3
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#   extra-dep: true
+#  subdirs:
+#  - auto-update
+#  - wai
+#
+# A package marked 'extra-dep: true' will only be built if demanded by a
+# non-dependency (i.e. a user package), and its test suites and benchmarks
+# will not be run. This is useful for tweaking upstream packages.
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver
+# (e.g., acme-missiles-0.3)
+# extra-deps: []
+
+# Override default flag values for local packages and extra-deps
+# flags: {}
+
+# Extra package databases containing global packages
+# extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.6"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor

Haskell-book/17/ListApplicative/test/Spec.hs

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+module Main where
+
+import Control.Applicative
+import Data.Monoid
+import Test.QuickCheck.Checkers
+import Test.QuickCheck.Classes
+import List
+import ZipList
+import Validation (Validation(..))
+
+main :: IO ()
+main = do
+    quickBatch $ applicative (Cons (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer)) Nil)
+    quickBatch $ monoid (ZipList' $ Cons (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer)) Nil)
+    quickBatch $ applicative (ZipList' $ Cons (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer)) Nil)
+    quickBatch $ applicative ((Success (Sum 1, Sum 2, Sum 3)) :: Validation String (Sum Integer, Sum Integer, Sum Integer))