src/HOL/Proofs/Extraction/Pigeonhole.thy

--- a/src/HOL/Proofs/Extraction/Pigeonhole.thy	Tue Jan 02 16:17:13 2018 +0100
+++ b/src/HOL/Proofs/Extraction/Pigeonhole.thy	Tue Jan 02 16:40:54 2018 +0100
@@ -5,7 +5,7 @@
 section \<open>The pigeonhole principle\<close>
 
 theory Pigeonhole
-imports Util "HOL-Library.Old_Datatype" "HOL-Library.Code_Target_Numeral"
+imports Util "HOL-Library.Realizers" "HOL-Library.Code_Target_Numeral"
 begin
 
 text \<open>