Solve 'Oh, so you like programming? Name all of the keywords!' kata

Author: borisskert

src/Keywords.hs

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+module Keywords (keywords) where
+
+-- https://www.codewars.com/kata/634ac4e77611b9f57dff456d/train/haskell
+
+keywords :: [String]
+keywords =
+  [ "_",
+    "module",
+    "where",
+    "let",
+    "if",
+    "else",
+    "case",
+    "in",
+    "infix",
+    "infixl",
+    "infixr",
+    "of",
+    "import",
+    "foreign",
+    "then",
+    "do",
+    "default",
+    "class",
+    "newtype",
+    "instance",
+    "deriving",
+    "type",
+    "data"
+  ]

test/KeywordsSpec.hs

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+module KeywordsSpec where
+
+import qualified Data.Set as S
+import Keywords (keywords)
+import Test.Hspec (Spec, it, shouldBe, shouldContain)
+import Test.Hspec.Core.Spec (Expectation)
+
+spec :: Spec
+spec = do
+  it "Do you have the correct number of keywords in your list?" $ do
+    length keywords `shouldBe` 23
+  it "Missing a word that is used when making a family of methods that can be used with related data types" $ do
+    keywords `shouldContainAll` ["module", "where"]
+  it "Missing a conditional word used in pattern matching (first word of a pair)" $ do
+    keywords `shouldContainAll` ["case"]
+  it "Missing a word that is used when making a family of methods that can be used with related data types" $ do
+    keywords `shouldContainAll` ["data", "type", "newtype", "instance", "class"]
+  it "Missing a word that defines the requirements for an instance to use a fallback method" $ do
+    keywords `shouldContainAll` ["default"]
+  it "Missing a word that allows you to write monadic computations in a more imperative style" $ do
+    keywords `shouldContainAll` ["do"]
+  it "Missing a conditional word that goes at the end" $ do
+    keywords `shouldContainAll` ["then", "else"]
+  it "Missing a word that is used when interfacing with C code" $ do
+    keywords `shouldContainAll` ["foreign"]
+  it "Missing a conditional word that determines a possibility" $ do
+    keywords `shouldContainAll` ["if"]
+  it "Missing a word used to obtain external modules" $ do
+    keywords `shouldContainAll` ["import"]
+  it "Missing a word used when substituting a name for a value (second word of a pair)" $ do
+    keywords `shouldContainAll` ["in"]
+  it "Missing a word used for functions that can be used in-between it's arguments" $ do
+    keywords `shouldContainAll` ["infix"]
+  it "Missing a word used at the top level that lets other files know what the current one is called" $ do
+    keywords `shouldContainAll` ["module"]
+  it "Missing a word used for functions that can be used in-between it's arguments (and can chain together from left-to-right)" $ do
+    keywords `shouldContainAll` ["infixl"]
+  it "Missing a word used for functions that can be used in-between it's arguments (and can chain together from right-to-left)" $ do
+    keywords `shouldContainAll` ["infixr"]
+  it "Missing a word used as a placeholder for data that you don't care about" $ do
+    keywords `shouldContainAll` ["_"]
+  it "Missing a conditional word used in pattern matching (second word of a pair)" $ do
+    keywords `shouldContainAll` ["of"]
+  it "Missing a word that saves a lot of boilerplate when defining behavior of new data types" $ do
+    keywords `shouldContainAll` ["deriving"]
+
+shouldContainAll :: (Show a, Ord a) => [a] -> [a] -> Expectation
+shouldContainAll actual expected =
+  S.fromList expected `S.isSubsetOf` S.fromList actual `shouldBe` True