--- a/src/Pure/theory.ML Thu Jul 04 11:26:00 2019 +0200
+++ b/src/Pure/theory.ML Thu Jul 04 12:31:24 2019 +0200
@@ -23,6 +23,7 @@
val defs_of: theory -> Defs.T
val at_begin: (theory -> theory option) -> theory -> theory
val at_end: (theory -> theory option) -> theory -> theory
+ val join_theory: theory list -> theory
val begin_theory: string * Position.T -> theory list -> theory
val end_theory: theory -> theory
val add_axiom: Proof.context -> binding * term -> theory -> theory
@@ -168,6 +169,11 @@
val defs_of = #defs o rep_theory;
+(* join theory *)
+
+val join_theory = foldl1 Context.join_thys;
+
+
(* begin/end theory *)
val begin_wrappers = rev o #1 o #wrappers o rep_theory;