Port raindrops test-suite to support Data.Text

Issue: #841

exercises/raindrops/.meta/hints.md

@@ -0,0 +1,34 @@
+## Hints
+
+You need to implement the `convert` function that returns number converted to
+raindrop sound. You can use the provided signature if you are unsure
+about the types, but don't let it restrict your creativity:
+
+```haskell
+convert :: Int -> String
+```
+
+This exercise works with textual data. For historical reasons, Haskell's
+`String` type is synonymous with `[Char]`, a list of characters. For more
+efficient handling of textual data, the `Text` type can be used.
+
+As an optional extension to this exercise, you can
+
+- Read about [string types](https://haskell-lang.org/tutorial/string-types) in Haskell.
+- Add `- text` to your list of dependencies in package.yaml.
+- Import `Data.Text` in [the following way](https://hackernoon.com/4-steps-to-a-better-imports-list-in-haskell-43a3d868273c):
+
+```haskell
+import qualified Data.Text as T
+import           Data.Text (Text)
+```
+
+- You can now write e.g. `convert :: Int -> Text` and refer to `Data.Text` combinators as e.g. `T.pack`.
+- Look up the documentation for [`Data.Text`](https://hackage.haskell.org/package/text-1.2.3.1/docs/Data-Text.html),
+- You can then replace all occurrences of `String` with `Text` in Raindrops.hs:
+
+```haskell
+convert :: Int -> Text
+```
+
+This part is entirely optional.

exercises/raindrops/examples/success-text/package.yaml

@@ -0,0 +1,17 @@
+name: raindrops
+
+dependencies:
+  - base
+  - text
+
+library:
+  exposed-modules: Raindrops
+  source-dirs: src
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - raindrops
+      - hspec

exercises/raindrops/examples/success-text/src/Raindrops.hs

@@ -0,0 +1,16 @@
+ {-# LANGUAGE OverloadedStrings #-}
+module Raindrops (convert) where
+
+import           Data.Maybe (fromMaybe)
+import qualified Data.Text as T
+import           Data.Text (Text)
+
+convert :: Int -> Text
+convert n = fromMaybe (T.pack $ show n) $
+  sound "Pling" 3 <>
+  sound "Plang" 5 <>
+  sound "Plong" 7
+  where
+    sound noise factor
+      | n `rem` factor == 0 = Just noise
+      | otherwise           = Nothing

exercises/raindrops/package.yaml

@@ -1,5 +1,5 @@
 name: raindrops
-version: 1.1.0.5
+version: 1.1.0.6
 
 dependencies:
   - base

exercises/raindrops/test/Tests.hs

@@ -1,8 +1,10 @@
 {-# OPTIONS_GHC -fno-warn-type-defaults #-}
+{-# LANGUAGE OverloadedStrings #-}
 
 import Data.Foldable     (for_)
 import Test.Hspec        (Spec, describe, it, shouldBe)
 import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+import Data.String       (fromString)
 
 import Raindrops (convert)
 
@@ -16,7 +18,7 @@ specs = describe "convert" $ for_ cases test
     test (number, expected) = it description assertion
       where
         description = show number
-        assertion   = convert number `shouldBe` expected
+        assertion   = convert number `shouldBe` fromString expected
 
     cases = [ (   1, "1"              )
             , (   3, "Pling"          )