Add statusFromNat function to retrieve Status from a KnownNat

servant/src/Servant/API/Status.hs

@@ -1,11 +1,16 @@
 {-# LANGUAGE DataKinds #-}
 -- Flexible instances is necessary on GHC 8.4 and earlier
 {-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 module Servant.API.Status where
 
 import Network.HTTP.Types.Status
 import GHC.TypeLits
 
+-- | Retrieve a known or unknown Status from a KnownNat
+statusFromNat :: forall a proxy. KnownNat a => proxy a -> Status
+statusFromNat = toEnum . fromInteger . natVal
+
 -- | Witness that a type-level natural number corresponds to a HTTP status code
 class KnownNat n => KnownStatus n where
   statusVal :: proxy n -> Status