Added HLint to the pipeline of test suites.

Notice the --reorder-goals switch in cabal install. More information about
it can be found at: haskell/cabal#1780.

HLint.hs

@@ -0,0 +1,7 @@
+{-# LANGUAGE PackageImports #-}
+
+module HLint () where
+
+import "hint" HLint.Default
+import "hint" HLint.Dollar
+import "hint" HLint.Generalise

README

@@ -4,7 +4,10 @@ cabal update                      # Download the most recent list of packages
 cabal install cabal-install       # Optional, can be prompted by cabal update
 
 cabal sandbox init                # Initialise the sandbox
-cabal install --only-dependencies # Install dependencies into the sandbox
+cabal install \                   # Install dependencies into the sandbox
+    --enable-tests \
+    --only-dependencies \
+    --reorder-goals
 cabal build                       # Build your package inside the sandbox
 
 cabal configure --enable-tests    # Enable the test suites

quickcheck-samples.cabal

@@ -20,3 +20,12 @@ Test-Suite spec
   Build-Depends:        base
                       , hspec
                       , QuickCheck
+
+Test-Suite style
+  Type:                 exitcode-stdio-1.0
+  Default-Language:     Haskell2010
+  Hs-Source-Dirs:       tests
+  Ghc-Options:          -Wall
+  Main-Is:              HLint.hs
+  Build-Depends:        base
+                      , hlint == 1.*

tests/HLint.hs

@@ -0,0 +1,16 @@
+module Main (main) where
+
+import Language.Haskell.HLint (hlint)
+import System.Exit            (exitFailure, exitSuccess)
+
+arguments :: [String]
+arguments =
+    [ "tests"
+    ]
+
+main :: IO ()
+main = do
+    hints <- hlint arguments
+    if null hints
+        then exitSuccess
+        else exitFailure