fix hlint-reported warnings

src/PaymentServer/Main.hs

@@ -204,7 +204,7 @@ logEndpoint endpoint =
 getApp :: ServerConfig -> IO Application
 getApp config =
   let
-    getIssuer ServerConfig{ issuer, signingKeyPath } = do
+    getIssuer ServerConfig{ issuer, signingKeyPath } =
       case (issuer, signingKeyPath) of
         (Trivial, Nothing) -> return $ Right trivialIssue
         (Ristretto, Just keyPath) -> do

src/PaymentServer/Processors/Stripe.hs

@@ -174,7 +174,7 @@ charge d key (Charges token voucher amount currency) = do
     Left StripeError {} -> throwError err400 { errBody = "Stripe charge didn't succeed" }
     where
       getCurrency :: Text -> Handler Currency
-      getCurrency maybeCurrency = do
+      getCurrency maybeCurrency =
         case readMaybe (unpack currency) of
           Just currency' -> return currency'
           Nothing -> throwError err400 { errBody = "Invalid currency specified" }

src/PaymentServer/Server.hs

 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeOperators #-}
-{-# LANGUAGE OverloadedStrings #-}
 
 -- | This module exposes a Servant-based Network.Wai server for payment
 -- interactions.