1 files changed, 11 insertions, 0 deletions

diff --git a/spec/src/Thermoprint/API.hs b/spec/src/Thermoprint/API.hs
index 4b10130..6c86008 100644
--- a/spec/src/Thermoprint/API.hs
+++ b/spec/src/Thermoprint/API.hs
@@ -22,8 +22,12 @@ import Data.Aeson
 
 import Data.Set (Set)
 import Data.Map (Map)
+import qualified Data.Map as Map (foldMapWithKey, singleton)
 import Data.Sequence (Seq)
 
+import Data.IntMap.Strict (IntMap)
+import qualified Data.IntMap.Strict as IntMap (foldMapWithKey, singleton)
+
 import Data.Text (Text)
 
 import GHC.Generics (Generic)
@@ -33,6 +37,13 @@ import Data.Proxy (Proxy(..))
 import Control.Exception (Exception)
 import Data.Typeable (Typeable)
 
+instance (Integral k, Ord k, ToJSON v) => ToJSON (Map k v) where
+  toJSON = toJSON . Map.foldMapWithKey (IntMap.singleton . castId)
+
+instance (Enum k, Ord k, FromJSON v) => FromJSON (Map k v) where
+  parseJSON = fmap (IntMap.foldMapWithKey $ Map.singleton . castId) . parseJSON
+       
+
 data PrinterStatus = Busy JobId
                    | Available
                    deriving (Generic, Show, FromJSON, ToJSON)