diff -r 978f7ca3329f -r 2cee31cd92f0 src/Pure/General/zstd.ML
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/General/zstd.ML	Fri Oct 21 16:39:31 2022 +0200
@@ -0,0 +1,19 @@
+(*  Title:      Pure/General/zstd.ML
+    Author:     Makarius
+
+Support for Zstd compression (via Isabelle/Scala).
+*)
+
+signature Zstd =
+sig
+  val compress: Bytes.T -> Bytes.T
+  val uncompress: Bytes.T -> Bytes.T
+end;
+
+structure Zstd: Zstd =
+struct
+
+val compress = \<^scala>\<open>Zstd.compress\<close>;
+val uncompress = \<^scala>\<open>Zstd.uncompress\<close>;
+
+end;