diff --git a/aeson-flowtyped.cabal b/aeson-flowtyped.cabal
--- a/aeson-flowtyped.cabal
+++ b/aeson-flowtyped.cabal
@@ -3,10 +3,12 @@
 -- see: https://github.com/sol/hpack
 
 name:           aeson-flowtyped
-version:        0.7.1
+version:        0.7.2
 synopsis:       Create Flow type definitions from Haskell data types.
 description:    Create Flow type definitions from Haskell data types.
 category:       Web
+homepage:       https://github.com/mikeplus64/aeson-flowtyped#readme
+bug-reports:    https://github.com/mikeplus64/aeson-flowtyped/issues
 author:         Mike Ledger <mike@quasimal.com>
 maintainer:     mike@quasimal.com
 license:        BSD3
@@ -14,6 +16,10 @@
 build-type:     Simple
 cabal-version:  >= 1.10
 
+source-repository head
+  type: git
+  location: https://github.com/mikeplus64/aeson-flowtyped
+
 library
   hs-source-dirs:
       src
@@ -50,4 +56,5 @@
     , aeson-flowtyped
     , tasty
     , tasty-hunit
+    , unordered-containers
   default-language: Haskell2010
diff --git a/src/Data/Aeson/Flow.hs b/src/Data/Aeson/Flow.hs
--- a/src/Data/Aeson/Flow.hs
+++ b/src/Data/Aeson/Flow.hs
@@ -125,7 +125,7 @@
 data FlowTypeF a
   = Object !(HashMap Text a)
   | ExactObject !(HashMap Text a)
-  | Map !(Vector (Text, a))
+  | ObjectMap !Text a
   | Array a
   | Tuple !(Vector a)
   | Fun !(Vector (Text, a)) a
@@ -139,7 +139,8 @@
   | Poly !Var !(Vector a)
   | PolyVar !Var
   deriving (Show, Eq, Functor, Traversable, Foldable)
--- XXX: vector >= 0.12 has Eq1 vector which allows us to derive eq
+-- XXX: vector >= 0.12 has Eq1 vector which allows us to use eq for Fix FlowTypeF
+-- and related types
 
 instance Show1 FlowTypeF where
   liftShowsPrec sp sl i a =
@@ -165,16 +166,12 @@
 ppAlts :: [FlowType] -> FlowType -> PP.Doc
 ppAlts alts (Fix f) = case f of
   Alt a b -> ppAlts (a:alts) b
-  x       -> PP.align
-             (sep
-              (map pp
-               (reverse (Fix x:alts))))
+  x       -> PP.align (sep (map pp (reverse (Fix x:alts))))
   where
     sep [x]    = x
     sep (x:xs) = x PP.<+> PP.string "|" PP.<$> sep xs
     sep _      = PP.empty
 
-
 braceList :: [PP.Doc] -> PP.Doc
 braceList =
   (\s -> PP.lbrace PP.</> s PP.</> PP.rbrace)
@@ -208,6 +205,7 @@
   Nullable _ -> PP.parens x
   Omitable _ -> PP.parens x
   Alt _ _    -> PP.parens x
+  Array _    -> PP.parens x
   _          -> x
 
 ppObject :: HashMap Text FlowType -> [PP.Doc]
@@ -220,6 +218,11 @@
 
 pp :: FlowType -> PP.Doc
 pp (Fix ft) = case ft of
+  ObjectMap keyName a -> braceList
+    [ PP.brackets (text keyName PP.<> PP.text ": string") PP.<>
+      PP.colon PP.<+>
+      pp a
+    ]
   Object hm -> braceList (ppObject hm)
   ExactObject hm -> braceBarList (ppObject hm)
   Array a -> mayWrap a (pp a) PP.<> PP.string "[]"
@@ -232,8 +235,8 @@
     Void    -> PP.text "void"
     Any     -> PP.text "any"
     Mixed   -> PP.text "mixed"
-  Nullable a -> PP.char '?' PP.<> pp a
-  Omitable a -> PP.char '?' PP.<> pp a -- hopefully these are caught
+  Nullable a -> PP.char '?' PP.<> mayWrap a (pp a)
+  Omitable a -> PP.char '?' PP.<> mayWrap a (pp a) -- hopefully these are caught
   Literal a -> ppJson a
   Tag t -> PP.squotes (text t)
   Name (FlowName _ t) -> text t
@@ -624,6 +627,12 @@
 instance Typeable a => FlowTyped (Fixed a) where
   isPrim  _ = False
   flowType _ = Fix (Prim Number)
+  flowTypeName _ = Nothing
+
+instance FlowTyped a => FlowTyped (HashMap Text a) where
+  -- XXX this is getting quite incoherent, what makes something "Prim" or not...
+  isPrim _ = True
+  flowType _ = Fix (ObjectMap "key" (flowTypePreferName (Proxy :: Proxy a)))
   flowTypeName _ = Nothing
 
 -- monomorphic numeric instances
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -3,6 +3,8 @@
 import           Data.Aeson            (Value)
 import           Data.Aeson.Flow
 import           Data.Functor.Foldable (Fix (..))
+import           Data.HashMap.Strict   (HashMap)
+import qualified Data.HashMap.Strict   as H
 import           Data.Proxy            (Proxy (..))
 import           Data.Text             (Text)
 import           Data.Vector           (Vector)
@@ -43,6 +45,11 @@
 
 instance FlowTyped Codep
 
+data Hmap = Hmap (HashMap Text User)
+  deriving (Generic)
+
+instance FlowTyped Hmap
+
 main :: IO ()
 main = defaultMain $ testGroup "aeson-flowtyped"
   [ testCase "nullable" $
@@ -92,6 +99,21 @@
     \  'C4' |\n\
     \  'D4';" @=?
     exportFlowTypeAs "Adt4" (flowType (Proxy :: Proxy Adt4))
+
+  , testCase "map-style object / hashmap instance" $
+    "export type Hmap =\n\
+    \  { [key: string]: User };" @=?
+    exportFlowTypeAs "Hmap" (flowType (Proxy :: Proxy (HashMap Text User)))
+
+  , testCase "parens around nullable array" $
+    "export type T =\n\
+    \  ?(string[]);" @=?
+    exportFlowTypeAs "T" (flowType (Proxy :: Proxy (Maybe [Text])))
+
+  , testCase "parens around nullable array of nullable elements" $
+    "export type T =\n\
+    \  ?((?string)[]);" @=?
+    exportFlowTypeAs "T" (flowType (Proxy :: Proxy (Maybe [Maybe Text])))
 
   , testCase "module export" $
     "// @flow\n\