CONTRIBUTORS

--- a/CONTRIBUTORS	Thu Mar 22 17:18:33 2018 +0100
+++ b/CONTRIBUTORS	Fri Mar 23 10:52:00 2018 +0100
@@ -6,6 +6,11 @@
 Contributions to this Isabelle version
 --------------------------------------
 
+* March 2018: Florian Haftmann
+  Abstract bit operations push_bit, push_take, push_drop, alongside
+  with an algebraic foundation for bit strings and word types in
+  HOL-ex.
+
 * March 2018: Viorel Preoteasa
   Generalisation of complete_distrib_lattice