From bc922190b70e1264f356ab463dda18babf7910e3 Mon Sep 17 00:00:00 2001
From: Abhinav Gupta <mail@abhinavg.net>
Date: Wed, 11 Mar 2015 00:26:58 -0700
Subject: [PATCH] [haskell] Derive Generic in generated types

---
 compiler/cpp/src/generate/t_hs_generator.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/compiler/cpp/src/generate/t_hs_generator.cc b/compiler/cpp/src/generate/t_hs_generator.cc
index b217ce6093b..638cc301c04 100644
--- a/compiler/cpp/src/generate/t_hs_generator.cc
+++ b/compiler/cpp/src/generate/t_hs_generator.cc
@@ -205,6 +205,7 @@ void t_hs_generator::init_generator() {
 string t_hs_generator::hs_language_pragma() {
   return string(
       "{-# LANGUAGE DeriveDataTypeable #-}\n"
+      "{-# LANGUAGE DeriveGeneric #-}\n"
       "{-# LANGUAGE OverloadedStrings #-}\n"
       "{-# OPTIONS_GHC -fno-warn-missing-fields #-}\n"
       "{-# OPTIONS_GHC -fno-warn-missing-signatures #-}\n"
@@ -241,6 +242,7 @@ string t_hs_generator::hs_imports() {
       "import qualified Data.Maybe as M (catMaybes)\n"
       "import qualified Data.Text.Lazy.Encoding as E ( decodeUtf8, encodeUtf8 )\n"
       "import qualified Data.Text.Lazy as LT\n"
+      "import qualified GHC.Generics as G (Generic)\n"
       "import qualified Data.Typeable as TY ( Typeable )\n"
       "import qualified Data.HashMap.Strict as Map\n"
       "import qualified Data.HashSet as Set\n"
@@ -302,7 +304,7 @@ void t_hs_generator::generate_enum(t_enum* tenum) {
     f_types_ << name;
     first = false;
   }
-  indent(f_types_) << "deriving (P.Show,P.Eq, TY.Typeable, P.Ord, P.Bounded)" << endl;
+  indent(f_types_) << "deriving (P.Show, P.Eq, G.Generic, TY.Typeable, P.Ord, P.Bounded)" << endl;
   indent_down();
 
   string ename = capitalize(tenum->get_name());
@@ -555,7 +557,7 @@ void t_hs_generator::generate_hs_struct_definition(ofstream& out,
     indent_down();
   }
 
-  out << " deriving (P.Show,P.Eq,TY.Typeable)" << endl;
+  out << " deriving (P.Show,P.Eq,G.Generic,TY.Typeable)" << endl;
 
   if (is_exception)
     out << "instance X.Exception " << tname << endl;