servant-polysemy-0.1.2: Utilities for using servant in a polysemy stack
Copyright(c) 2020 Alex Chapman
Safe HaskellNone



A simple usage scenario is that you create your API, then implement a server for it in a 'ServerT api (Sem (Error ServerError ': r))' monad (where api is your API type), then run it with runWarpServer. See example/Server.hs for a trivial example of this.

If you need to take your Servant-Polysemy server and run it in an ordinary Servant server then you can use hoistServerIntoSem. This can be used to e.g. add Swagger docs to your server, as in example/ServerWithSwagger.hs.


Use ordinary Servant code in a Polysemy Sem

hoistServerIntoSem :: forall api r. (HasServer api '[], Members '[Error ServerError, Embed IO] r) => Server api -> ServerT api (Sem r) Source #

Hoist an ordinary Servant Server into a ServerT whose monad is Sem, so that it can be used with serveSem.

liftHandler :: Members '[Error ServerError, Embed IO] r => Handler a -> Sem r a Source #

Make a Servant Handler run in a Polysemy Sem instead.

Use Servant-Polysemy code in an ordinary Servant/WAI system

serveSem :: forall api r. HasServer api '[] => (forall x. Sem r x -> IO x) -> ServerT api (Sem (Error ServerError ': r)) -> Application Source #

Turn a ServerT that contains a Sem (as returned by hoistServerIntoSem) into a WAI Application.

semHandler :: (forall x. Sem r x -> IO x) -> Sem (Error ServerError ': r) a -> Handler a Source #

Turn a Sem that can throw ServerErrors into a Servant Handler.

Use Warp to serve a Servant-Polysemy API in a Sem stack.

runWarpServer Source #


:: forall api r. (HasServer api '[], Member (Embed IO) r) 
=> Port

The port to listen on, e.g. '8080'

-> Bool

Whether to show exceptions in the http response (good for debugging but potentially a security risk)

-> ServerT api (Sem (Error ServerError ': r))

The server to run. You can create one of these with hoistServerIntoSem.

-> Sem r () 

Run the given server on the given port, possibly showing exceptions in the responses.

runWarpServerSettings :: forall api r. (HasServer api '[], Member (Embed IO) r) => Settings -> ServerT api (Sem (Error ServerError ': r)) -> Sem r () Source #

Run the given server with these Warp settings.

Redirect paths in a Servant-Polysemy API

type Redirect (code :: Nat) loc = Verb 'GET code '[JSON] (Headers '[Header "Location" loc] NoContent) Source #

A redirect response with the given code, the new location given in the given type, e.g: > Redirect 302 Text This will return a '302 Found' response, and we will use Text in the server to say where it will redirect to.

redirect :: ToHttpApiData a => a -> Sem r (Headers '[Header "Location" a] NoContent) Source #

Serve a redirect response to the given location, e.g: > redirect "apiv1"