Add remaining haskell book exercises

Haskell-book/26/Embedded/Embedded.cabal

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+-- This file has been generated from package.yaml by hpack version 0.20.0.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: 4aaf9c578000b87231817edc542c283c58e2e1562cc290df37e9e8a9628885b0
+
+name:           Embedded
+version:        0.1.0.0
+author:         Eugen Wissner
+maintainer:     belka@caraus.de
+copyright:      2018 Eugen Wissner
+license:        BSD3
+build-type:     Simple
+cabal-version:  >= 1.10
+
+library
+  hs-source-dirs:
+      src
+  build-depends:
+      base >=4.7 && <5
+    , transformers
+  exposed-modules:
+      OuterInner
+  other-modules:
+      Paths_Embedded
+  default-language: Haskell2010
+
+test-suite Embedded-test
+  type: exitcode-stdio-1.0
+  main-is: Spec.hs
+  hs-source-dirs:
+      test
+  ghc-options: -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      Embedded
+    , base >=4.7 && <5
+    , transformers
+  other-modules:
+      Paths_Embedded
+  default-language: Haskell2010

Haskell-book/26/Embedded/Setup.hs

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+import Distribution.Simple
+main = defaultMain

Haskell-book/26/Embedded/package.yaml

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

Haskell-book/26/Embedded/src/OuterInner.hs

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+module OuterInner where
+
+import Control.Monad.Trans.Except
+import Control.Monad.Trans.Maybe
+import Control.Monad.Trans.Reader
+
+-- We only need to use return once
+-- because it's one big Monad
+embedded :: MaybeT
+            (ExceptT String
+                    (ReaderT () IO))
+            Int
+--embedded = return 1
+embedded = MaybeT . ExceptT . ReaderT $ return . (const (Right (Just 1)))
+
+-- We can sort of peel away the layers one by one:
+maybeUnwrap :: ExceptT String
+               (ReaderT () IO) (Maybe Int)
+maybeUnwrap = runMaybeT embedded
+
+-- Next
+eitherUnwrap :: ReaderT () IO
+                (Either String (Maybe Int))
+eitherUnwrap = runExceptT maybeUnwrap
+
+-- Lastly
+readerUnwrap :: ()
+             -> IO (Either String
+                           (Maybe Int))
+readerUnwrap = runReaderT eitherUnwrap

Haskell-book/26/Embedded/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-11.7
+
+# 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/26/Embedded/test/Spec.hs

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