Complete chapter 13

13-building-projects/13.14-chapter-exercises.md

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+# Chapter Exercises
+## Hangman game logic
+see hangman/src/Main.hs
+
+## Modifying code
+1. see src/ciphers.hs
+2. see src/palindrome.hs
+3. see src/person.hs

13-building-projects/13.7-check-your-understanding.md

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+# Intermission: Check your understanding
+1. `forever` and `when`
+2. `Data.Bits` and `Database.Blacktip.Types`
+3. The types used for the blacktip library
+4. 
+    1. `Control.Concurrent.MVar`, `Filesystem.Path.CurrentOS` and `Control.Concurrent`
+    2. `import qualifed Filesystem as FS`
+    3. `import Control.Monad (forever, when)`

13-building-projects/hangman/LICENSE

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+Copyright Author name here (c) 2017
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Author name here nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

13-building-projects/hangman/README.md

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+# hangman

13-building-projects/hangman/Setup.hs

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+import Distribution.Simple
+main = defaultMain

13-building-projects/hangman/hangman.cabal

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+name:                hangman
+version:             0.1.0.0
+-- synopsis:
+-- description:
+homepage:            https://github.com/githubuser/hangman#readme
+license:             BSD3
+license-file:        LICENSE
+author:              Gaël Depreeuw
+maintainer:          example@example.com
+copyright:           2017 Gaël Depreeuw
+category:            Game
+build-type:          Simple
+cabal-version:       >=1.10
+extra-source-files:  README.md,
+                     data/dict.txt
+
+executable hangman
+  hs-source-dirs:      src
+  main-is:             Main.hs
+  default-language:    Haskell2010
+  build-depends:       base >= 4.7 && < 5,
+                       random,
+                       split

13-building-projects/hangman/src/Main.hs

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+module Main where
+
+import Control.Monad (forever)
+import Data.Char (toLower, isAlpha)
+import Data.Maybe (isJust)
+import Data.List (intersperse)
+import System.Exit (exitSuccess)
+import System.Random (randomRIO)
+
+newtype WordList = WordList [String] deriving (Eq, Show)
+
+allWords :: IO WordList
+allWords = do
+  dict <- readFile "data/dict.txt"
+  return (WordList $ lines dict)
+
+minWordLength :: Int
+minWordLength = 5
+
+maxWordLength :: Int
+maxWordLength = 9
+
+maxWrongGuesses :: Int
+maxWrongGuesses = 10
+
+gameWords :: IO WordList
+gameWords = do
+  WordList aw <- allWords
+  return $ WordList (filter gameLength aw)
+  where gameLength w = 
+          let l = length (w :: String)
+          in l >= minWordLength && l < maxWordLength
+             && all isAlpha w
+
+randomWord :: WordList -> IO String
+randomWord (WordList wl) = do
+  randomIndex <- randomRIO (0, length wl - 1)
+  return $ wl !! randomIndex
+
+randomWord' :: IO String
+randomWord' = gameWords >>= randomWord
+
+data Puzzle = Puzzle String [Maybe Char] [Char] Int
+instance Show Puzzle where
+  show (Puzzle _ discovered guessed i) =
+    (intersperse ' ' $ fmap renderPuzzleChar discovered)
+    ++ " Guessed so far: " ++ guessed ++ "\n"
+    ++ "Wrong guesses so far: " ++ show i
+
+freshPuzzle :: String -> Puzzle
+freshPuzzle s = Puzzle s l [] 0
+    where l = fmap (const Nothing) s
+
+charInWord :: Puzzle -> Char -> Bool
+charInWord (Puzzle s _ _ _) c = elem c s
+
+alreadyGuessed :: Puzzle -> Char -> Bool
+alreadyGuessed (Puzzle _ _ s _) c = elem c s
+
+renderPuzzleChar :: Maybe Char -> Char
+renderPuzzleChar Nothing = '_'
+renderPuzzleChar (Just c) = c
+
+fillInCharacter :: Puzzle -> Char -> Puzzle
+fillInCharacter (Puzzle word filledInSoFar s i) c =
+  Puzzle word newFilledInSoFar (c:s) i
+  where newFilledInSoFar = zipWith (zipper c) word filledInSoFar
+        zipper guessed wordChar guessChar =
+          if wordChar == guessed
+          then Just wordChar
+          else guessChar
+ 
+handleWrongGuess :: Puzzle -> Puzzle
+handleWrongGuess (Puzzle w f g i) =
+  Puzzle w f g (i+1)
+
+handleGuess :: Puzzle -> Char -> IO Puzzle
+handleGuess puzzle guess = do
+  putStrLn $ "Your guess was: " ++ [guess]
+  case (charInWord puzzle guess, alreadyGuessed puzzle guess) of
+    (_, True) -> do
+      putStrLn "You already guessed that character, pick something else!"
+      return puzzle
+    (True, _) -> do
+      putStrLn "This character was in the word, filling in the word\
+               \ accordingly"
+      return (fillInCharacter puzzle guess)
+    (False, _) -> do
+      putStrLn "This character wasn't in the word, try again."
+      return $ handleWrongGuess (fillInCharacter puzzle guess)
+
+gameOver :: Puzzle -> Int -> IO ()
+gameOver (Puzzle wordToGuess _ _ i) maxWrong =
+  if i >= maxWrong then
+    do putStrLn "You lose"
+       putStrLn $ "The word was: " ++ wordToGuess
+       exitSuccess
+  else return ()
+
+gameWin :: Puzzle -> IO ()
+gameWin (Puzzle _ filledInSoFar _ _) =
+  if all isJust filledInSoFar then
+    do putStrLn "You win!"
+       exitSuccess
+  else return ()
+
+runGame :: Puzzle -> IO ()
+runGame puzzle = forever $ do
+  gameOver puzzle maxWrongGuesses
+  gameWin puzzle
+  putStrLn $ "Current puzzle is: " ++ show puzzle
+  putStr "Guess a letter: "
+  guess <- getLine
+  case guess of
+    [c] -> handleGuess puzzle c >>= runGame
+    _   -> putStrLn "Your guess must be a single character"
+
+
+main :: IO ()
+main = do
+  word <- randomWord'
+  let puzzle = freshPuzzle (fmap toLower word)
+  runGame puzzle

13-building-projects/hangman/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-9.10
+
+# 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: ">=1.5"
+#
+# 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

13-building-projects/hello

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+Subproject commit dc97b6e0d15ae6d63c32f7b7fa35291270835552

13-building-projects/src/cipher.hs

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+module Cipher where
+
+    import Data.Char
+    
+    -- Chapter 9.12
+    caesar :: String -> Int -> String
+    caesar [] _ = []
+    caesar (x:xs) k
+        | isAlpha x = go x k ++ caesar xs k
+        | otherwise = caesar xs k
+        where go c key = [enc c (+) key]
+
+    unCaesar :: String -> Int -> String
+    unCaesar [] _ = []
+    unCaesar (x:xs) k
+        | isAlpha x = go x k ++ unCaesar xs k
+        | otherwise = caesar xs k
+        where go c key = [enc c (-) key]
+    
+    enc :: Char -> (Int -> Int -> Int) -> Int -> Char
+    enc c f k
+        | elem c ['a'..'z'] = chr (i 'a')
+        | elem c ['A'..'Z'] = chr (i 'A')
+        | otherwise = c
+        where i b  = (mod (ci b) r) + (ord b)
+              ci b = f ((ord c) - (ord b)) k
+              r = 26
+
+    alphaIndex :: Char -> Int
+    alphaIndex c
+        | elem c ['a'..'z'] = ord c - ord 'a'
+        | elem c ['A'..'Z'] = ord c - ord 'A'
+        | otherwise = 0
+
+
+    shift :: Char -> Char -> Char
+    shift c k
+        | elem c ['a'..'z'] = go c k 'a'
+        | elem c ['A'..'Z'] = go c k 'A'
+        | otherwise = c
+        where go p key base = chr $ (mod rel r) + b
+                where rel = alphaIndex p + alphaIndex key
+                      r = 26
+                      b = ord base
+
+    -- nice solution, but maps keyword to non-alpha characters
+    -- e.g. MEET_AT_DAWN 
+    --      ALLYALLYALLY
+    vigenere' :: [Char] -> [Char] -> [Char]
+    vigenere' xs ys = zipWith shift xs ((concat . repeat) ys)
+
+    -- wrote own zipWith variant which maps only when isAlpha
+    vigenere :: [Char] -> [Char] -> [Char]
+    vigenere xs [] = xs -- necessary to avoid bottom
+    vigenere xs ys = myZipWith shift xs ys
+        where myZipWith _ [] _  = []
+              myZipWith f s [] = myZipWith f s ys
+              myZipWith f (a:as) k@(b:bs) =
+                if isAlpha a
+                then f a b : myZipWith f as bs
+                else     a : myZipWith f as k
+
+    -- 1
+    -- Not a lot of error checking, but just testing
+    -- reading the input
+    callCaesar :: IO ()
+    callCaesar = do
+        putStrLn "Enter the plain text:"
+        s <- getLine
+        putStr "Enter the key (Char): "
+        c <- getChar
+        putStr "\n"
+        putStrLn $ caesar s $ alphaIndex c
+
+    callVigenere :: IO ()
+    callVigenere = do
+        putStrLn "Enter the plain text:"
+        s <- getLine
+        putStr "Enter the key (String): "
+        k <- getLine
+        putStr "\n"
+        putStrLn $ vigenere s k

13-building-projects/src/palindrome.hs

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+module Palindrome where
+
+import Control.Monad
+import Data.Char
+
+palindrome :: IO ()
+palindrome = forever $ do
+    line1 <- getLine
+    case (pal line1) of
+        True -> putStrLn "It's a palindrome!"
+        False -> putStrLn "Nope!"
+    where pal s = 
+           let s' = map toLower $ filter isAlpha s
+           in s' == reverse s'
+        

13-building-projects/src/person.hs

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+module Person where
+
+type Name = String
+type Age = Integer
+
+data Person = Person Name Age deriving Show
+
+data PersonInvalid =
+    NameEmpty
+  | AgeTooLow
+  | PersonInvalidUnknown String
+  deriving (Show, Eq)
+
+mkPerson :: Name -> Age -> Either PersonInvalid Person
+mkPerson name age
+    | name /= "" && age > 0 = Right $ Person name age
+    | name == "" = Left NameEmpty
+    | not (age > 0) = Left AgeTooLow
+    | otherwise =
+        Left $ PersonInvalidUnknown $
+            "Name was: " ++ show name ++
+            " Age was: " ++ show age
+
+gimmePerson :: IO ()
+gimmePerson = do
+    putStr "Provide a name: "
+    name <- getLine
+    putStr "Provide an age: "
+    age <- getLine
+    let p = mkPerson name ((read age) :: Integer)
+    case go p of
+        True  -> putStr "Yay! Succefully got a person: "
+        False -> putStrLn "Error: "
+    putStrLn $ show p
+    where go (Right _) = True
+          go (Left _)  = False