diff --git a/app/Main.hs b/app/Main.hs
index de1c1ab..05079da 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -1,6 +1,38 @@
 module Main where
 
-import Lib
+import           Options.Applicative
+import           Data.Semigroup                 ( (<>) )
+
+data CliFlags = CliFlags { inputFile :: String
+                         , inPlace :: Bool
+                         , configFile :: String
+                         } deriving (Show, Eq)
+
+-- | The parser for command line arguments, to be used with
+-- optparse-applicative
+cliParse :: Parser CliFlags
+cliParse =
+    CliFlags
+        <$> strArgument (metavar "INPUT" <> help "The input filename")
+        <*> switch
+                (  long "in-place"
+                <> short 'i'
+                <> help
+                       "Whether to modify the file in-place (this is a destructive operation"
+                )
+        <*> strOption
+                (long "config" <> metavar "CONFIG" <> help "The config filename"
+                )
+
+
+printFile :: CliFlags -> IO ()
+printFile (CliFlags _ filename _) = print filename
 
 main :: IO ()
-main = someFunc
+main = printFile =<< execParser opts
+  where
+    opts =
+        info (cliParse <**> helper)
+            $  fullDesc
+            <> progDesc "Format a markdown file"
+            <> header "mdfmt - a markdown formatter"
diff --git a/package.yaml b/package.yaml
index 8ad2bde..29aaca0 100644
--- a/package.yaml
+++ b/package.yaml
@@ -18,9 +18,14 @@ extra-source-files:
 # complications of embedding Haddock markup inside cabal files, it is
 # common to point users to the README.md file.
 description:         Please see the README on GitHub at <https://github.com/afnanenayet/mdfmt#readme>
+default-extensions: OverloadedStrings
 
 dependencies:
 - base >= 4.7 && < 5
+- cmark
+- optparse-applicative
+- text
+- word-wrap
 
 library:
   source-dirs: src
@@ -46,3 +51,4 @@ tests:
     - -with-rtsopts=-N
     dependencies:
     - mdfmt
+    - QuickCheck
diff --git a/src/Lib.hs b/src/Lib.hs
index d36ff27..f1de174 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -1,6 +1,24 @@
 module Lib
-    ( someFunc
-    ) where
+    ( wordWrap
+    , WordWrapError
+    )
+where
 
-someFunc :: IO ()
-someFunc = putStrLn "someFunc"
+import qualified Data.Text                     as T
+
+-- | An error representing what can go wrong when performing a word wrap
+data WordWrapError a = InvalidColumnWidth Int
+
+-- | Word wrap some text to the desired column length
+wordWrap :: T.Text -> Int -> Either (WordWrapError a) T.Text
+wordWrap input width | width < 1 = Left $ InvalidColumnWidth width
+                     | otherwise = Right $ T.intercalate "\n" wrappedLines
+  where
+    wrappedLines = map T.unwords $ gobble 0 [] $ T.words input
+    gobble :: Int -> [T.Text] -> [T.Text] -> [[T.Text]]
+    gobble _ acc [] = [reverse acc]
+    gobble k acc ws@(w : rest)
+        | 1 >= width     = reverse acc : [w] : gobble 0 [] rest
+        | k + 1 >= width = reverse acc : gobble 0 [] ws
+        | otherwise      = gobble (k + l + 1) (w : acc) rest
+        where l = T.length w
diff --git a/stack.yaml.lock b/stack.yaml.lock
new file mode 100644
index 0000000..ac9a8f3
--- /dev/null
+++ b/stack.yaml.lock
@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    size: 525663
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/14/14.yaml
+    sha256: 6edc48df46eb8bf7b861e98dd30d021a92c2e1820c9bb6528aac5d997b0e14ef
+  original: lts-14.14
diff --git a/test/Spec.hs b/test/Spec.hs
index cd4753f..21a31a0 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -1,2 +1,31 @@
+import           Test.QuickCheck
+import qualified Data.Text                     as T
+import           Data.Either
+import           Lib
+import           Text.Wrap
+
 main :: IO ()
-main = putStrLn "Test suite not yet implemented"
+main = do
+    quickCheckWith stdArgs { maxSuccess = 100000 } prop_wordsAreWrapped
+
+printWordWrap :: Show b => Either a b -> IO ()
+printWordWrap (Left  _   ) = print "error"
+printWordWrap (Right text) = print text
+
+prop_wordsAreWrapped :: [Char] -> Int -> Bool
+prop_wordsAreWrapped slowString width
+    | length wrappedLines < 1 = True
+    | otherwise               = maxLineSize <= expectedLineLength
+  where
+    input  = T.pack slowString
+    result = wrapText
+        (WrapSettings { preserveIndentation = True, breakLongWords = False })
+        width
+        input
+    wrappedLines       = T.lines result
+    maxLineSize        = maximum $ map T.length wrappedLines
+    maxWordSize        = maximum $ map T.length $ T.words input
+    -- if there is a word that's longer than the given width, then the
+    -- line will have to be as long as the longest word (at minimum)
+    expectedLineLength = max width (maxWordSize + 1)
+