type alias for stripe secret key

src/PaymentServer/Main.hs

@@ -93,7 +93,7 @@ data ServerConfig = ServerConfig
   , database        :: Database
   , databasePath    :: Maybe Text
   , endpoint        :: Endpoint
-  , stripeKey    :: ByteString
+  , stripeKey       :: ByteString
   }
   deriving (Show, Eq)
 

src/PaymentServer/Processors/Stripe.hs

@@ -77,6 +77,8 @@ import PaymentServer.Persistence
   , VoucherDatabase(payForVoucher)
   )
 
+type StripePrivateKey = ByteString
+
 data Acknowledgement = Ok
 
 instance ToJSON Acknowledgement where
@@ -94,7 +96,7 @@ getVoucher (MetaData []) = Nothing
 getVoucher (MetaData (("Voucher", value):xs)) = Just value
 getVoucher (MetaData (x:xs)) = getVoucher (MetaData xs)
 
-stripeServer :: VoucherDatabase d => d -> ByteString -> Server StripeAPI
+stripeServer :: VoucherDatabase d => d -> StripePrivateKey -> Server StripeAPI
 stripeServer d key = webhook d
                      :<|> charge d key
 
@@ -143,7 +145,7 @@ instance FromJSON Charges where
 
 -- | call the stripe Charge API (with token, voucher in metadata, amount, currency etc
 -- and if the Charge is okay, then set the voucher as "paid" in the database.
-charge :: VoucherDatabase d => d -> ByteString -> Charges -> Handler Acknowledgement
+charge :: VoucherDatabase d => d -> StripePrivateKey -> Charges -> Handler Acknowledgement
 charge d key (Charges token voucher amount currency) = do
   let config = StripeConfig (StripeKey key) Nothing
       tokenId = TokenId token