Add the haskell book

Haskell-book/08/.gitignore

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+/bower_components/
+/node_modules/
+/.pulp-cache/
+/output/
+/generated-docs/
+/.psc*
+/.purs*
+/.psa*

Haskell-book/08/bower.json

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+{
+  "name": "08",
+  "ignore": [
+    "**/.*",
+    "node_modules",
+    "bower_components",
+    "output"
+  ],
+  "dependencies": {
+    "purescript-prelude": "^3.1.0",
+    "purescript-console": "^3.0.0",
+    "purescript-tuples": "^4.1.0",
+    "purescript-generics-rep": "^5.3.0",
+    "purescript-arrays": "^4.2.1",
+    "purescript-foldable-traversable": "^3.6.1",
+    "purescript-unfoldable": "^3.0.0",
+    "purescript-maybe": "^3.0.0"
+  },
+  "devDependencies": {
+    "purescript-psci-support": "^3.0.0"
+  }
+}

Haskell-book/08/src/Exercises.purs

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+module Exercises where
+    
+import Data.Tuple (Tuple(..), fst, snd)
+import Prelude
+
+--
+-- Reviewing currying
+--
+cattyConny :: String -> String -> String
+cattyConny x y = x <> " mrow " <> y
+
+flippy :: String -> String -> String
+flippy = flip cattyConny
+
+appedCatty :: String -> String
+appedCatty = cattyConny "woops"
+
+frappe :: String -> String
+frappe = flippy "haha"
+
+--
+-- Recursion
+--
+-- Exercise 2
+sumNumbers :: Int -> Int
+sumNumbers x = sumNumbers' x 0
+    where sumNumbers' 0 acc = 0
+          sumNumbers' n acc = n + (sumNumbers' (n - 1) acc)
+
+-- Exercise 2
+multiply :: Int -> Int -> Int
+multiply _ 0 = 0
+multiply x 1 = x
+multiply x y = x + multiply x (y - 1)
+
+--
+-- Fixing dividedBy
+--
+data DividedResult =
+      Result Int
+    | DividedByZero
+
+instance showDividedResult :: Show DividedResult where
+    show :: DividedResult -> String
+    show (Result n)    = show n
+    show DividedByZero = show "Divided by zero"
+
+go :: Int -> Int -> Int -> Tuple Int Int
+go n d count
+    | n < d     = Tuple count n
+    | otherwise = go (n - d) d (count + 1)
+
+abs :: Int -> Int
+abs x
+    | x < 0     = -x
+    | otherwise = x
+
+dividedBy :: Int -> Int -> Tuple DividedResult DividedResult
+dividedBy num denom
+    | denom == 0        = Tuple DividedByZero DividedByZero
+    | (num * denom) < 0 = let tuple = go (abs num) (abs denom) 0 in
+                                Tuple (Result (-(fst tuple))) (Result (snd tuple))
+    | otherwise         = let tuple = go (abs num) (abs denom) 0 in
+                                Tuple (Result (fst tuple)) (Result (snd tuple))
+
+--
+-- McCarthy 91 function
+--
+mc91 :: Int -> Int
+mc91 n
+    | n > 100   = n - 10
+    | otherwise = mc91 (mc91 (n + 11))

Haskell-book/08/src/Main.purs

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+module Main where
+
+import Prelude
+import Control.Monad.Eff (Eff)
+import Control.Monad.Eff.Console (CONSOLE, log)
+
+main :: forall e. Eff (console :: CONSOLE | e) Unit
+main = do
+  log "Hello sailor!"

Haskell-book/08/src/WordNumber.purs

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+module WordNumber where
+
+import Data.Array (reverse)
+import Data.Maybe (Maybe(..))
+import Data.String (joinWith)
+import Data.Tuple (Tuple(..))
+import Data.Unfoldable (unfoldr)
+import Prelude
+
+digitToWord :: Int -> String
+digitToWord 0 = "null"
+digitToWord 1 = "one"
+digitToWord 2 = "two"
+digitToWord 3 = "three"
+digitToWord 4 = "four"
+digitToWord 5 = "five" 
+digitToWord 6 = "six"
+digitToWord 7 = "seven"
+digitToWord 8 = "eight"
+digitToWord 9 = "nine"
+digitToWord _ = ""
+
+digits :: Int -> Array Int
+digits n = reverse $ unfoldr unfold n
+    where unfold x
+              | x == 0    = Nothing
+              | otherwise = Just (Tuple (mod x 10) (div x 10))
+
+wordNumber :: Int -> String
+wordNumber n = joinWith "-" $ map digitToWord (digits n)

Haskell-book/08/test/Main.purs

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+module Test.Main where
+
+import Prelude
+import Control.Monad.Eff (Eff)
+import Control.Monad.Eff.Console (CONSOLE, log)
+
+main :: forall e. Eff (console :: CONSOLE | e) Unit
+main = do
+  log "You should add some tests."