Add remaining haskell book exercises

Haskell-book/17/Combinations.hs

@@ -0,0 +1,12 @@
+module Combinations where
+
+import Control.Applicative (liftA3)
+
+stops :: String
+stops = "pbtdkg"
+
+vowels :: String
+vowels = "aeiou"
+
+combos :: [a] -> [b] -> [c] -> [(a, b, c)]
+combos = liftA3 (\x y z -> (x, y, z))

Haskell-book/17/Constant.hs

@@ -0,0 +1,13 @@
+module Constant where
+
+newtype Constant a b =
+    Constant { getConstant :: a }
+    deriving (Eq, Ord, Show)
+
+instance Functor (Constant a) where
+    fmap _ (Constant x) = Constant x
+
+instance Monoid a
+  => Applicative (Constant a) where
+      pure x = Constant mempty
+      (Constant x) <*> (Constant y) = Constant $ mappend x y

Haskell-book/17/Exercises/.gitignore

@@ -0,0 +1,3 @@
+.stack-work/
+Exercises.cabal
+*~

Haskell-book/17/Exercises/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

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

@@ -0,0 +1,6 @@
+module Main where
+
+import Exercises
+
+main :: IO ()
+main = return ()

Haskell-book/17/Exercises/package.yaml

@@ -0,0 +1,35 @@
+name:                Exercises
+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:
+  Exercises-exe:
+    main:                Main.hs
+    source-dirs:         app
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - Exercises
+
+tests:
+  Exercises-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - Exercises

Haskell-book/17/Exercises/src/Exercises.hs

@@ -0,0 +1,124 @@
+module Exercises where
+
+import Test.QuickCheck
+import Test.QuickCheck.Checkers
+
+--- 1
+data Pair a = Pair a a deriving (Show, Eq)
+
+instance Functor Pair where
+    fmap f (Pair x y) = Pair (f x) (f y)
+
+instance Applicative Pair where
+    pure f = Pair f f
+    (Pair f f') <*> (Pair x y) = Pair (f x) (f' y)
+
+instance Arbitrary a => Arbitrary (Pair a) where
+    arbitrary = do
+        x <- arbitrary
+        y <- arbitrary
+        return $ Pair x y
+
+instance Eq a => EqProp (Pair a) where
+    (=-=) = eq
+
+--- 2
+data Two a b  = Two a b deriving (Show, Eq)
+
+instance Functor (Two a) where
+    fmap f (Two x y) = Two x (f y)
+
+instance Monoid a => Applicative (Two a) where
+    pure x = Two mempty $ x
+    (Two f f') <*> (Two x y) = Two (mappend f x) (f' y)
+
+instance (Arbitrary a, Arbitrary b) => Arbitrary (Two a b) where
+    arbitrary = do
+        x <- arbitrary
+        y <- arbitrary
+        return $ Two x y
+
+instance (Eq a, Eq b) => EqProp (Two a b) where
+    (=-=) = eq
+
+--- 3
+data Three a b c  = Three a b c deriving (Show, Eq)
+
+instance Functor (Three a b) where
+    fmap f (Three x y z) = Three x y (f z)
+
+instance (Monoid a, Monoid b) => Applicative (Three a b) where
+    pure x = Three mempty mempty x
+    (Three f f' f'') <*> (Three x y z) = Three (mappend f x) (mappend f' y) (f'' z)
+
+instance (Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (Three a b c) where
+    arbitrary = do
+        x <- arbitrary
+        y <- arbitrary
+        z <- arbitrary
+        return $ Three x y z
+
+instance (Eq a, Eq b, Eq c) => EqProp (Three a b c) where
+    (=-=) = eq
+
+--- 4
+data Three' a b = Three' a b b deriving (Show, Eq)
+
+instance Functor (Three' a) where
+    fmap f (Three' x y z) = Three' x (f y) (f z)
+
+instance (Monoid a) => Applicative (Three' a) where
+    pure x = Three' mempty x x
+    (Three' f f' f'') <*> (Three' x y z) = Three' (mappend f x) (f' y) (f'' z)
+
+instance (Arbitrary a, Arbitrary b) => Arbitrary (Three' a b) where
+    arbitrary = do
+        x <- arbitrary
+        y <- arbitrary
+        z <- arbitrary
+        return $ Three' x y z
+
+instance (Eq a, Eq b) => EqProp (Three' a b) where
+    (=-=) = eq
+
+--- 5
+data Four a b c d = Four a b c d deriving (Show, Eq)
+
+instance Functor (Four a b c) where
+    fmap f (Four x y z t) = Four x y z (f t)
+
+instance (Monoid a, Monoid b, Monoid c) => Applicative (Four a b c) where
+    pure x = Four mempty mempty mempty x
+    (Four f f' f'' f''') <*> (Four x y z t) = Four (mappend f x) (mappend f' y) (mappend f'' z) (f''' t)
+
+instance (Arbitrary a, Arbitrary b, Arbitrary c, Arbitrary d) => Arbitrary (Four a b c d) where
+    arbitrary = do
+        x <- arbitrary
+        y <- arbitrary
+        z <- arbitrary
+        t <- arbitrary
+        return $ Four x y z t
+
+instance (Eq a, Eq b, Eq c, Eq d) => EqProp (Four a b c d) where
+    (=-=) = eq
+
+--- 5
+data Four' a b = Four' a a a b deriving (Show, Eq)
+
+instance Functor (Four' a) where
+    fmap f (Four' x y z t) = Four' x y z (f t)
+
+instance (Monoid a) => Applicative (Four' a) where
+    pure x = Four' mempty mempty mempty x
+    (Four' f f' f'' f''') <*> (Four' x y z t) = Four' (mappend f x) (mappend f' y) (mappend f'' z) (f''' t)
+
+instance (Arbitrary a, Arbitrary b) => Arbitrary (Four' a b) where
+    arbitrary = do
+        x <- arbitrary
+        y <- arbitrary
+        z <- arbitrary
+        t <- arbitrary
+        return $ Four' x y z t
+
+instance (Eq a, Eq b) => EqProp (Four' a b) where
+    (=-=) = eq

Haskell-book/17/Exercises/stack.yaml

@@ -0,0 +1,66 @@
+# 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/Exercises/test/Spec.hs

@@ -0,0 +1,26 @@
+import Data.Monoid
+import Exercises
+import Test.QuickCheck.Checkers
+import Test.QuickCheck.Classes
+
+main :: IO ()
+main = do
+    quickBatch $ functor $ Pair ('a', 'b', 'c') ('d', 'e', 'f')
+    quickBatch $ applicative $ Pair ('a', 'b', 'c') ('d', 'e', 'f')
+    quickBatch $ functor $ Two ('a', 'b', 'c') (1 :: Integer, 2 :: Integer, 3 :: Integer)
+    quickBatch $ applicative $ Two (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                   (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer))
+    quickBatch $ applicative $ Three (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                     (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer))
+                                     (Sum (4 :: Integer), Sum (5 :: Integer), Sum (6 :: Integer))
+    quickBatch $ applicative $ Three' (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                      (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer))
+                                      (Sum (4 :: Integer), Sum (5 :: Integer), Sum (6 :: Integer))
+    quickBatch $ applicative $ Four (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                    (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                    (Sum (1 :: Integer), Sum (2 :: Integer), Sum (3 :: Integer))
+                                    (Sum (4 :: Integer), Sum (5 :: Integer), Sum (6 :: Integer))
+    quickBatch $ applicative $ Four (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                    (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                    (Product (1 :: Integer), Product (2 :: Integer), Product (3 :: Integer))
+                                    (Sum (4 :: Integer), Sum (5 :: Integer), Sum (6 :: Integer))

Haskell-book/17/FixerUpper.hs

@@ -0,0 +1,6 @@
+module FixerUpper where
+
+a = const <$> Just <$> "Hello" <*> "World"
+
+b = (,,,) <$> Just 90
+    <*> Just 10 <*> Just "Tierness" <*> pure [1, 2, 3]

Haskell-book/17/Identity.hs

@@ -0,0 +1,9 @@
+newtype Identity a = Identity a
+    deriving (Eq, Show, Ord)
+
+instance Functor Identity where
+    fmap f (Identity x) = Identity $ f x
+
+instance Applicative Identity where
+    pure x = Identity x
+    (Identity f) <*> (Identity y) = Identity $ f y

Haskell-book/17/ListApplicative/.gitignore

@@ -0,0 +1,3 @@
+.stack-work/
+ListApplicative.cabal
+*~

Haskell-book/17/ListApplicative/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

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

@@ -0,0 +1,6 @@
+module Main where
+
+import List
+
+main :: IO ()
+main = return ()

Haskell-book/17/ListApplicative/package.yaml

@@ -0,0 +1,35 @@
+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

@@ -0,0 +1,46 @@
+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

@@ -0,0 +1,27 @@
+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

@@ -0,0 +1,40 @@
+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

@@ -0,0 +1,66 @@
+# 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

@@ -0,0 +1,16 @@
+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))