Add OpenApi support.

bucks.cabal

@@ -19,6 +19,11 @@ flag aeson
      default:         False
      manual:          True
 
+flag openapi
+     description:     Enable OpenAPI instances
+     default:         False
+     manual:          True
+
 flag rel8
      description:     Enable Rel8 support
      default:         False
@@ -38,6 +43,10 @@ library
        other-modules: Data.Money.JSON
        build-depends: aeson >= 2.0 && < 3.0
        ghc-options:   -DUSE_AESON
+    if flag(openapi)
+       other-modules: Data.Money.OpenApi
+       build-depends: openapi3
+       ghc-options:   -DUSE_OPENAPI
     if flag(rel8)
        other-modules: Data.Money.Rel8
        build-depends: rel8 >= 1.4,

src/Data/Money.hs

@@ -7,6 +7,9 @@ import Data.Money.Internal as Export
 #ifdef USE_AESON
 import Data.Money.JSON as Export ()
 #endif
+#ifdef USE_OPENAPI
+import Data.Money.OpenApi as Export ()
+#endif
 #ifdef USE_REL8
 import Data.Money.Rel8 as Export ()
 #endif

src/Data/Money/OpenApi.hs

@@ -0,0 +1,22 @@
+{-# OPTIONS_GHC -Wno-orphans #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE MonoLocalBinds #-}
+{-# LANGUAGE OverloadedLists #-}
+{-# LANGUAGE OverloadedStrings #-}
+module Data.Money.OpenApi where
+
+import Data.Fixed
+import Data.Money.Internal
+import Data.OpenApi
+import Data.Typeable
+
+instance (KnownCurrency c, Typeable (Money c)) => ToSchema (Money c) where
+  declareNamedSchema _ = do
+    centiSchema <- declareSchemaRef (Proxy :: Proxy Centi)
+    strSchema <- declareSchemaRef (Proxy :: Proxy String)
+    return $ NamedSchema (Just "Money") $
+      mempty { _schemaType = Just OpenApiObject
+             , _schemaProperties = [ ("currency", strSchema)
+                                   , ("amount", centiSchema) ]
+             , _schemaRequired = [ "currency", "amount" ]
+             }

stack.yaml

@@ -6,6 +6,7 @@ packages:
 flags:
   bucks:
     aeson: true
+    openapi: true
     rel8: true
 
 nix: