diff --git a/Data/GraphQL/Execute.hs b/Data/GraphQL/Execute.hs
index 1f921aa..1abda00 100644
--- a/Data/GraphQL/Execute.hs
+++ b/Data/GraphQL/Execute.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE CPP #-}
-module Data.GraphQL.Execute where
+module Data.GraphQL.Execute (execute) where
 
 #if !MIN_VERSION_base(4,8,0)
 import Control.Applicative ((<$>), pure)
@@ -17,20 +17,28 @@ import Data.GraphQL.AST
 import Data.GraphQL.Schema (Resolver, Schema(..))
 import qualified Data.GraphQL.Schema as Schema
 
-execute :: (Alternative m, Monad m) => Schema m -> Schema.Subs -> Document -> m Aeson.Value
+execute
+  :: (Alternative m, Monad m)
+  => Schema m -> Schema.Subs -> Document -> m Aeson.Value
 execute (Schema resolv) f doc = selectionSet f resolv =<< query doc
 
 query :: Alternative f => Document -> f SelectionSet
-query (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) =
-  pure sels
+query (Document [DefinitionOperation (Query (Node _varDefs _ _ sels))]) = pure sels
 query  _ = empty
 
-selectionSet :: Alternative f => Schema.Subs -> Resolver f -> SelectionSet -> f Aeson.Value
-selectionSet f resolv = fmap (Aeson.Object . fold) . traverse (selection f resolv)
+selectionSet
+  :: Alternative f
+  => Schema.Subs -> Resolver f -> SelectionSet -> f Aeson.Value
+selectionSet f resolv = fmap (Aeson.Object . fold)
+                      . traverse (selection f resolv)
 
-selection :: Alternative f => Schema.Subs -> Resolver f -> Selection -> f Aeson.Object
+selection
+  :: Alternative f
+  => Schema.Subs -> Resolver f -> Selection -> f Aeson.Object
 selection f resolv (SelectionField field@(Field alias name _ _ _)) =
-    fmap (HashMap.singleton aliasOrName) $ Aeson.toJSON <$> resolv (fieldToInput f field)
+    fmap (HashMap.singleton aliasOrName)
+      $  Aeson.toJSON
+     <$> resolv (fieldToInput f field)
   where
     aliasOrName = if T.null alias then name else alias
 selection _ _ _ = empty
@@ -48,6 +56,7 @@ argument _ _ = error "argument: not implemented yet"
 
 fieldToInput :: Schema.Subs -> Field -> Schema.Input
 fieldToInput f (Field _ n as _ sels) =
+    -- TODO: Get rid of `catMaybes`, invalid arguments should raise an error
     Schema.InputField n (catMaybes $ argument f <$> as)
                         (fieldToInput f . selectionToField <$> sels)
 
diff --git a/Data/GraphQL/Schema.hs b/Data/GraphQL/Schema.hs
index 8d63696..4ec3748 100644
--- a/Data/GraphQL/Schema.hs
+++ b/Data/GraphQL/Schema.hs
@@ -10,7 +10,7 @@ import Data.Aeson (ToJSON(toJSON))
 import Data.HashMap.Strict (HashMap)
 import Data.Text (Text, pack)
 
-data Schema f = Schema (QueryRoot f) -- (Maybe  MutationRoot)
+data Schema f = Schema (QueryRoot f)
 
 type QueryRoot f = Resolver f
 
@@ -21,8 +21,6 @@ data Output = OutputObject (HashMap Text Output)
             | OutputScalar Scalar
             | OutputEnum Text
               deriving (Show)
-           -- | OutputUnion [Output]
-           -- | OutputNonNull (Output)
 
 type Argument = (Text, Scalar)
 
@@ -31,7 +29,7 @@ type Subs = Text -> Maybe Scalar
 data Input = InputField Text [Argument] [Input]
              deriving (Show)
 
--- TODO: Make ScalarInt Int32
+-- TODO: GraphQL spec for Integer Scalar is 32bits
 data Scalar = ScalarInt     Int
             | ScalarFloat   Double
             | ScalarString  Text
@@ -40,7 +38,7 @@ data Scalar = ScalarInt     Int
               deriving (Show)
 
 instance IsString Scalar where
-  fromString = ScalarString . pack
+    fromString = ScalarString . pack
 
 instance ToJSON Scalar where
     toJSON (ScalarInt     x) = toJSON x
diff --git a/stack.yaml b/stack.yaml
index ed928ac..93788d8 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-5.2
+resolver: lts-5.3
 packages:
 - '.'
 extra-deps: []