@@ -24,8 +24,10 @@ import qualified Elm.Compiler.Type.Extract as Extract
2424import qualified Elm.Interface as I
2525import qualified Elm.Name as N
2626import qualified Elm.Package as Pkg
27+import qualified Elm.Compiler.Version as Version
2728import qualified Generate.JavaScript.Builder as JS
2829import qualified Generate.JavaScript.Name as Name
30+import qualified Json.Encode as Encode
2931import qualified Optimize.DecisionTree as DT
3032import qualified Reporting.Region as R
3133
@@ -868,10 +870,17 @@ generateMain mode interfaces home segments main =
868870 # List.foldl' addDot elm segments
869871
870872 Opt.Dynamic decoder msgType ->
873+ let
874+ jsonMetadata =
875+ Encode.object
876+ [ ("versions", Encode.object [ ("elm", Pkg.encodeVersion Version.version) ])
877+ , ("types", Type.encodeMetadata (Extract.fromMsg interfaces msgType))
878+ ]
879+ in
871880 JS.Ref (Name.fromGlobal home "main")
872881 # List.foldl' addDot elm segments
873882 # generateJsExpr mode decoder
874− # JS.Json (Type.encodeMetadata (Extract.fromMsg interfaces msgType))
883+ # JS.Json jsonMetadata
875884
876885
877886(#) :: JS.Expr -> JS.Expr -> JS.Expr