2 files changed, 24 insertions, 1 deletions
diff --git a/src/Language/GraphQL/AST/Document.hs b/src/Language/GraphQL/AST/Document.hs
index ea640df..131285d 100644
--- a/src/Language/GraphQL/AST/Document.hs
+++ b/src/Language/GraphQL/AST/Document.hs
@@ -464,6 +464,14 @@ data SchemaExtension
 newtype Description = Description (Maybe Text)
     deriving (Eq, Show)
 
+instance Semigroup Description
+  where
+    Description lhs <> Description rhs = Description $ lhs <> rhs
+
+instance Monoid Description
+  where
+    mempty = Description mempty
+
 -- ** Types
 
 -- | Type definitions describe various user-defined types.
diff --git a/src/Language/GraphQL/AST/Encoder.hs b/src/Language/GraphQL/AST/Encoder.hs
index a58a161..d19b9e6 100644
--- a/src/Language/GraphQL/AST/Encoder.hs
+++ b/src/Language/GraphQL/AST/Encoder.hs
@@ -72,7 +72,8 @@ typeSystemDefinition formatter = \case
             $ optempty (directives formatter) operationDirectives
             <> "schema "
             <> bracesList formatter operationTypeDefinition (NonEmpty.toList operationTypeDefinitions')
-    _ -> "" -- TODO: TypeDefinition and DerictiveDefinition missing.
+    Full.TypeDefinition typeDefinition' -> typeDefinition formatter typeDefinition'
+    _ -> "" -- TODO: DerictiveDefinition missing.
   where
     operationTypeDefinition (Full.OperationTypeDefinition operationType' namedType')
         = indentLine (incrementIndent formatter)
@@ -80,6 +81,20 @@ typeSystemDefinition formatter = \case
         <> colon formatter
         <> Lazy.Text.fromStrict namedType'
 
+typeDefinition :: Formatter -> Full.TypeDefinition -> Lazy.Text.Text
+typeDefinition formatter = \case
+    Full.ScalarTypeDefinition description' name' directives'
+        -> optempty (description formatter) description'
+        <> "scalar "
+        <> Lazy.Text.fromStrict name'
+        <> optempty (directives formatter) directives'
+    _typeDefinition' -> "" -- TODO: Types missing.
+
+description :: Formatter -> Full.Description -> Lazy.Text.Text
+description _formatter (Full.Description Nothing) = ""
+description formatter (Full.Description (Just description')) =
+    stringValue formatter description'
+
 -- | Converts a t'Full.ExecutableDefinition' into a string.
 definition :: Formatter -> Full.ExecutableDefinition -> Lazy.Text
 definition formatter x