fixed the doctests

shell.nix

@@ -0,0 +1,13 @@
+let
+  rev = "16d475334409f7fa632929b2838421b4ffe34927";
+  _nixpkgs = import <nixpkgs> { };
+  pkgs = import ( fetchTarball "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz" ) { };
+  ghc = pkgs.haskellPackages;
+  ghcPackages = ghc.ghcWithPackages (ps: [ ps.protolude ps.turtle ]);
+in with pkgs;
+
+stdenv.mkDerivation {
+  name = "gpm";
+  buildInputs = [ ghcPackages ];
+  buildDepends = [ libiconv ];
+}

src-doctest/Main.hs

@@ -4,4 +4,11 @@ import System.FilePath.Glob
 import Test.DocTest
 
 main :: IO ()
-main = glob "src/**/*.hs" >>= doctest
+main = do
+  files <- glob "src/**/*.hs"
+  doctest (params <> files)
+  where
+    params = [ "-XOverloadedStrings"
+             , "-XNoImplicitPrelude"
+             , "-XScopedTypeVariables"
+             ]

src-exe/Main.hs

@@ -32,8 +32,8 @@ data AppOptions = AppOptions { genMode :: GenMode
 
 optParser :: Parser AppOptions
 optParser = AppOptions
-            <$> (fromMaybe Short <$> optional (opt toGenMode "gen" 'g' "Possible values: short, dict"))
-            <*> optional (optPath "dict" 'd' "dictionary (predefined names are: english, first-names, generic, literary) or use any file path (one word per line)")
+            <$> (fromMaybe Short <$> optional (opt toGenMode "gen" 'g' "Possible values: short, lovecraftian, dict"))
+            <*> optional (optPath "dict" 'd' "dictionary file path (the file should contain one word per line)")
             <*> optional (optInt "len" 'n' "complexity depends on the gen chosen")
 
 toGenMode :: Text -> Maybe GenMode

src/HFIG/Helpers.hs

@@ -15,14 +15,14 @@ module HFIG.Helpers
   )
 where
 
-import Protolude
+import           Protolude
 
-import qualified System.Random.MWC as Random
 import qualified Control.Monad.Primitive as Prim
-import qualified Data.Vector as V
-import           Data.Vector ((!))
+import           Data.Vector             ((!))
+import qualified Data.Vector             as V
+import qualified System.Random.MWC       as Random
 
-import qualified Data.Text as Text
+import qualified Data.Text               as Text
 
 -- | Generic id generator from using nameparts
 idgen :: Text -> NameParts -> Int -> IO Text