Servant with GADT types experiment

ServantGADT.hs

{-#LANGUAGE GADTs #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeOperators #-}

module Lib where

import Servant
import Servant.API ()

data Query t where
    GetInt :: Int -> Query Int
    GetInts :: Query [Int]

-- | API Type
type QueryAPI t =
    "query" :> ReqBody '[JSON] (Query t) :> Post '[JSON] t

server :: Server (QueryAPI t)
server = handleQuery
    where
        handleQuery :: Query t -> Handler t
        handleQuery (GetInt i) = return i
        handleQuery GetInts = return [1]