introduction to ranges

hkata.cabal

@@ -12,6 +12,7 @@ library
   hs-source-dirs:      src
   exposed-modules:     HelloWorld
                        , ListKata.Extract
+                       , ListKata.Ranges
   build-depends:       base >= 4.7 && < 5
   default-language:    Haskell2010
 

src/ListKata/Ranges.hs

@@ -0,0 +1 @@
+module ListKata.Ranges where

test/ListKata/RangesSpec.hs

@@ -0,0 +1,21 @@
+module ListKata.RangesSpec where
+
+import Test.Hspec
+import Test.QuickCheck
+import ListKata.Ranges
+
+spec :: Spec
+spec = do
+  describe "range syntax and usage" $ do
+    it "gives a shorthand for a list" $
+      [1..10] `shouldBe` [1,2,3,4,5,6,7,8,9,10]
+    it "defines steps" $
+      [2,4..10] `shouldBe` [2,4,6,8,10]
+  describe "cycling through a range" $
+    it "goes forever, so remember to take" $
+      take 6 (cycle [1..3]) `shouldBe` [1,2,3,1,2,3]
+  describe "repeating an item" $ do
+    it "goes forever, so remember to take" $
+      take 6 (repeat 'a') `shouldBe` "aaaaaa"
+    it "better expressed by replicate" $
+      replicate 6 'a' `shouldBe` "aaaaaa"