diff --git a/CHANGELOG.md b/CHANGELOG.md
index dafe975..612fc1a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,16 @@
 All notable changes to this project will be documented in this file.
 
 ## Unreleased
+### Deprecated
+- `Language.GraphQL.AST.Arguments`. Use `[Language.GraphQL.AST.Argument]`
+  instead.
+- `Language.GraphQL.AST.Directives`. Use `[Language.GraphQL.AST.Directives]`
+  instead.
+- `Language.GraphQL.AST.VariableDefinitions`. Use
+  `[Language.GraphQL.AST.VariableDefinition]` instead.
+
+### Added
+- Module documentation.
 
 ## [0.5.0.1] - 2019-09-10
 ### Added
diff --git a/src/Language/GraphQL/AST.hs b/src/Language/GraphQL/AST.hs
index 0c0ed89..dc7f6ac 100644
--- a/src/Language/GraphQL/AST.hs
+++ b/src/Language/GraphQL/AST.hs
@@ -45,18 +45,20 @@ type Document = NonEmpty Definition
 -- * Operations
 
 -- | Top-level definition of a document, either an operation or a fragment.
-data Definition = DefinitionOperation OperationDefinition
-                | DefinitionFragment  FragmentDefinition
-                  deriving (Eq, Show)
+data Definition
+    = DefinitionOperation OperationDefinition
+    | DefinitionFragment FragmentDefinition
+    deriving (Eq, Show)
 
 -- | Operation definition.
-data OperationDefinition = OperationSelectionSet SelectionSet
-                         | OperationDefinition   OperationType
-                                                 (Maybe Name)
-                                                 VariableDefinitions
-                                                 Directives
-                                                 SelectionSet
-                           deriving (Eq, Show)
+data OperationDefinition
+    = OperationSelectionSet SelectionSet
+    | OperationDefinition OperationType
+                          (Maybe Name)
+                          [VariableDefinition]
+                          [Directive]
+                          SelectionSet
+    deriving (Eq, Show)
 
 -- | GraphQL has 3 operation types: queries, mutations and subscribtions.
 --
@@ -73,7 +75,7 @@ type SelectionSetOpt = [Selection]
 
 -- | Single selection element.
 data Selection
-    = SelectionField          Field
+    = SelectionField Field
     | SelectionFragmentSpread FragmentSpread
     | SelectionInlineFragment InlineFragment
     deriving (Eq, Show)
@@ -82,12 +84,13 @@ data Selection
 
 -- | GraphQL field.
 data Field
-    = Field (Maybe Alias) Name Arguments Directives SelectionSetOpt
+    = Field (Maybe Alias) Name [Argument] [Directive] SelectionSetOpt
     deriving (Eq, Show)
 
 -- * Arguments
 
 -- | Argument list.
+{-# DEPRECATED Arguments "Use [Argument] instead" #-}
 type Arguments = [Argument]
 
 -- | Argument.
@@ -96,15 +99,15 @@ data Argument = Argument Name Value deriving (Eq,Show)
 -- * Fragments
 
 -- | Fragment spread.
-data FragmentSpread = FragmentSpread Name Directives deriving (Eq, Show)
+data FragmentSpread = FragmentSpread Name [Directive] deriving (Eq, Show)
 
 -- | Inline fragment.
-data InlineFragment = InlineFragment (Maybe TypeCondition) Directives SelectionSet
+data InlineFragment = InlineFragment (Maybe TypeCondition) [Directive] SelectionSet
                       deriving (Eq, Show)
 
 -- | Fragment definition.
 data FragmentDefinition
-    = FragmentDefinition Name TypeCondition Directives SelectionSet
+    = FragmentDefinition Name TypeCondition [Directive] SelectionSet
     deriving (Eq, Show)
 
 {-# DEPRECATED FragmentName "Use Name instead" #-}
@@ -135,6 +138,7 @@ data ObjectField = ObjectField Name Value deriving (Eq, Show)
 -- * Variables
 
 -- | Variable definition list.
+{-# DEPRECATED VariableDefinitions "Use [VariableDefinition] instead" #-}
 type VariableDefinitions = [VariableDefinition]
 
 -- | Variable definition.
@@ -158,6 +162,7 @@ data NonNullType = NonNullTypeNamed Name
 -- * Directives
 
 -- | Directive list.
+{-# DEPRECATED Directives "Use [Directive] instead" #-}
 type Directives = [Directive]
 
 -- | Directive.
diff --git a/src/Language/GraphQL/Encoder.hs b/src/Language/GraphQL/Encoder.hs
index 63a0ef2..b3ec655 100644
--- a/src/Language/GraphQL/Encoder.hs
+++ b/src/Language/GraphQL/Encoder.hs
@@ -67,11 +67,11 @@ operationDefinition formatter (OperationDefinition Mutation name vars dirs sels)
     = "mutation " <> node formatter name vars dirs sels
 
 node :: Formatter
-     -> Maybe Name
-     -> VariableDefinitions
-     -> Directives
-     -> SelectionSet
-     -> Text
+    -> Maybe Name
+    -> [VariableDefinition]
+    -> [Directive]
+    -> SelectionSet
+    -> Text
 node formatter name vars dirs sels
     = Text.Lazy.fromStrict (fold name)
     <> optempty (variableDefinitions formatter) vars
@@ -170,7 +170,7 @@ directive :: Formatter -> Directive -> Text
 directive formatter (Directive name args)
     = "@" <> Text.Lazy.fromStrict name <> optempty (arguments formatter) args
 
-directives :: Formatter -> Directives -> Text
+directives :: Formatter -> [Directive] -> Text
 directives formatter@(Pretty _) = Text.Lazy.cons ' ' . spaces (directive formatter)
 directives Minified = spaces (directive Minified)
 
diff --git a/src/Language/GraphQL/Parser.hs b/src/Language/GraphQL/Parser.hs
index 6d403b2..bbe1de7 100644
--- a/src/Language/GraphQL/Parser.hs
+++ b/src/Language/GraphQL/Parser.hs
@@ -69,7 +69,7 @@ alias = try $ name <* colon
 
 -- * Arguments
 
-arguments :: Parser Arguments
+arguments :: Parser [Argument]
 arguments = parens $ some argument
 
 argument :: Parser Argument
@@ -135,7 +135,7 @@ objectField = ObjectField <$> name <* symbol ":" <*> value
 
 -- * Variables
 
-variableDefinitions :: Parser VariableDefinitions
+variableDefinitions :: Parser [VariableDefinition]
 variableDefinitions = parens $ some variableDefinition
 
 variableDefinition :: Parser VariableDefinition
@@ -164,7 +164,7 @@ nonNullType = NonNullTypeNamed <$> name <* bang
 
 -- * Directives
 
-directives :: Parser Directives
+directives :: Parser [Directive]
 directives = some directive
 
 directive :: Parser Directive