Add remaining haskell book exercises

Haskell-book/25/Bifunctor/.gitignore

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

Haskell-book/25/Bifunctor/Setup.hs

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+import Distribution.Simple
+main = defaultMain

Haskell-book/25/Bifunctor/package.yaml

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+name:                Bifunctor
+version:             0.1.0.0
+license:             BSD3
+author:              "Eugen Wissner"
+maintainer:          "belka@caraus.de"
+copyright:           "2018 Eugen Wissner"
+
+dependencies:
+- base >= 4.7 && < 5
+
+library:
+  source-dirs: src
+
+tests:
+  Bifunctor-test:
+    main:                Spec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - Bifunctor

Haskell-book/25/Bifunctor/src/Bifunctor.hs

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+{-# LANGUAGE NoImplicitPrelude #-}
+module Bifunctor where
+
+import Prelude (($), id, (.))
+
+class Bifunctor p where
+    {-# MINIMAL bimap | first, second #-}
+
+    bimap :: (a -> b)
+          -> (c -> d)
+          -> p a c
+          -> p b d
+    bimap f g = first f . second g
+
+    first :: (a -> b) -> p a c -> p b c
+    first f = bimap f id
+
+    second :: (b -> c) -> p a b -> p a c
+    second = bimap id
+
+-- 1
+data Deux a b = Deux a b
+
+instance Bifunctor Deux where
+    first f (Deux a c) = Deux (f a) c
+    second f (Deux a b) = Deux a (f b)
+
+-- 2
+data Const a b = Const a
+
+instance Bifunctor Const where
+    first f (Const a) = Const (f a)
+    second f (Const a) = Const a
+
+-- 3
+data Drei a b c = Drei a b c
+
+instance Bifunctor (Drei a) where
+    first f (Drei a b c) = Drei a (f b) c
+    second f (Drei a b c) = Drei a b (f c)
+
+-- 4
+data SuperDrei a b c = SuperDrei a b
+
+instance Bifunctor (SuperDrei a) where
+    first f (SuperDrei a b) = SuperDrei a (f b)
+    second f (SuperDrei a b) = SuperDrei a b
+
+-- 5
+data SemiDrei a b c = SemiDrei a
+
+instance Bifunctor (SemiDrei a) where
+    first f (SemiDrei a) = SemiDrei a
+    second f (SemiDrei a) = SemiDrei a
+
+-- 6
+data Quadriceps a b c d = Quadzzz a b c d
+
+instance Bifunctor (Quadriceps a b) where
+    first f (Quadzzz a b c d) = Quadzzz a b (f c) d
+    second f (Quadzzz a b c d) = Quadzzz a b c (f d)
+
+-- 7
+data Either a b = Left a | Right b
+
+instance Bifunctor Either where
+    first f (Left a) = Left $ f a
+    second f (Right b) = Right $ f b

Haskell-book/25/Bifunctor/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-11.6
+
+# 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/25/Bifunctor/test/Spec.hs

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+main :: IO ()
+main = putStrLn "Test suite not yet implemented"