Parser: add ApplicativeDo

Author: Anton-Latukha

src/Nix/Parser.hs

@@ -5,6 +5,7 @@
 {-# LANGUAGE DeriveGeneric #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ApplicativeDo #-}
 
 {-# OPTIONS_GHC -fno-warn-name-shadowing #-}
 {-# OPTIONS_GHC -Wno-missing-signatures #-}