Very, very alpha implementation of Twirp service generation for Haskell.
This project provides a number of things:
- A protoc plugin for generating a Haskell Twirp service (based on Servant) for Services defined in a proto file.
- A haskell library,
twirpfor quickly serving up the generated application.
It requires the use of proto-lens to generate haskell datatypes from proto messages.
An example, end-to-end application is included in app.
- Install
protoc(e.g.,brew install protoc) - Install the required protoc plugins:
cabal install proto-lens-protocgo get github.com/tclem/twirp-haskell/protoc-gen-twirp_haskellgo get github.com/tclem/proto-lens-jsonpb/protoc-gen-jsonpb_haskell
Use the protoc plugin to generate a twirp service and associated protobuf types from a proto file.
protoc -I=. --proto_path=./proto \
--plugin=protoc-gen-haskell=`which proto-lens-protoc` --haskell_out=./app \
--jsonpb_haskell_out=./app \
--plugin=protoc-gen-twirp_haskell=./script/run-twirp_haskell --twirp_haskell_out=./app/Twirp/Example/Haberdasher \
haberdasher.proto
The result is a couple of files that describe your service. First, here are the types that define a Servant API:
-- Code generated by protoc-gen-twirp_haskell 0.1.0, DO NOT EDIT.
{-# LANGUAGE TypeOperators #-}
module Twirp.Example.Haberdasher.Haberdasher where
import Servant
import Twirp
import Proto.Haberdasher
-- This is an example set of twirp services.
type HaberdasherAPI
= "twirp" :> "twirp.example.haberdasher.Haberdasher" :> HaberdasherService
:<|> "twirp" :> "twirp.example.haberdasher.Health" :> HealthService
-- Haberdasher service makes hats for clients.
type HaberdasherService
-- MakeHat produces a hat of mysterious, randomly-selected color!
= "MakeHat" :> ReqBody [Protobuf, JSON] Size :> Post '[Protobuf, JSON] Hat
-- Get paid
:<|> "GetBill" :> ReqBody [Protobuf, JSON] Hat :> Post '[Protobuf, JSON] Bill
-- Health check service
type HealthService
= "Check" :> ReqBody [Protobuf, JSON] Ping :> Post '[Protobuf, JSON] PongThe datatypes are defined in Proto.Haberdasher.
Plugging this into an existing warp/wai server is straightforward. See app/Main.hs for the full details:
type RequestID = String
type API
= Header "X-Request-Id" RequestID
:> HaberdasherAPI
main :: IO ()
main = run 8003 app
app :: Application
app = twirpErrorResponses apiApp
apiApp :: Application
apiApp = serve (Proxy :: Proxy API) server
server :: Server API
server _requestID = (makeHat :<|> getBill) :<|> checkHealth