Provide `Network.GRPC.HighLevel.Client.simplifyServerStreaming` (#82)

src/Network/GRPC/HighLevel/Client.hs

@@ -31,6 +31,7 @@ module Network.GRPC.HighLevel.Client
 
   -- * Client utility functions
   , acquireClient
+  , simplifyServerStreaming
   , simplifyUnary
   )
 
@@ -147,20 +148,57 @@ acquireClient cfg impl = do
   c <- managed (LL.withClient g cfg)
   liftIO (impl c)
 
--- | A utility for simplifying gRPC client requests in common cases; you can use
--- this to avoid 'ClientRequest' and 'ClientResponse' pattern-matching
+-- | A utility for simplifying server-streaming gRPC client requests; you can
+-- use this to avoid 'ClientRequest' and 'ClientResult' pattern-matching
 -- boilerplate at call sites.
+simplifyServerStreaming :: TimeoutSeconds
+                           -- ^ RPC call timeout, in seconds
+                        -> MetadataMap
+                           -- ^ RPC call metadata
+                        -> (ClientError -> IO StatusDetails)
+                           -- ^ Handler for client errors
+                        -> (StatusCode -> StatusDetails -> IO StatusDetails)
+                           -- ^ Handler for non-StatusOk response
+                        -> (ClientRequest 'ServerStreaming request response
+                            -> IO (ClientResult 'ServerStreaming response))
+                           -- ^ Endpoint implementation (typically generated by grpc-haskell)
+                        -> request
+                           -- ^ Request payload
+                        -> (MetadataMap -> StreamRecv response -> IO ())
+                           -- ^ Stream handler; note that the 'StreamRecv'
+                           -- action must be called repeatedly in order to
+                           -- consume the stream
+                        -> IO StatusDetails
+simplifyServerStreaming timeout meta clientError nonStatusOkError f x handler = do
+
+  let request = ClientReaderRequest x timeout meta handler
+
+  response <- f request
+
+  case response of
+    ClientReaderResponse _ StatusOk details
+      -> pure details
+
+    ClientReaderResponse _ statusCode details
+      -> nonStatusOkError statusCode details
+
+    ClientErrorResponse err
+      -> clientError err
+
+-- | A utility for simplifying unary gRPC client requests; you can use this to
+-- avoid 'ClientRequest' and 'ClientResult' pattern-matching boilerplate at
+-- call sites.
 simplifyUnary :: TimeoutSeconds
                 -- ^ RPC call timeout, in seconds
               -> MetadataMap
                  -- ^ RPC call metadata
-              -> (ClientError -> IO (b, StatusDetails))
+              -> (ClientError -> IO (response, StatusDetails))
                  -- ^ Handler for client errors
-              -> (b -> StatusCode -> StatusDetails -> IO (b, StatusDetails))
+              -> (response -> StatusCode -> StatusDetails -> IO (response, StatusDetails))
                  -- ^ Handler for non-StatusOK responses
-              -> (ClientRequest 'Normal a b -> IO (ClientResult 'Normal b))
-                 -- ^ gRPC function implementation (typically generated by gRPC-haskell)
-              -> (a -> IO (b, StatusDetails))
+              -> (ClientRequest 'Normal request response -> IO (ClientResult 'Normal response))
+                 -- ^ Endpoint implementation (typically generated by grpc-haskell)
+              -> (request -> IO (response, StatusDetails))
                  -- ^ The simplified happy-path (StatusOk) unary call action
 simplifyUnary timeout meta clientError nonStatusOkError f x = do