diff -r fe9d746b273e -r bf2fecda8383 src/Tools/Haskell/Markup.hs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Tools/Haskell/Markup.hs	Sat Nov 03 19:33:15 2018 +0100
@@ -0,0 +1,28 @@
+{- GENERATED by Isabelle! -}
+{-  Title:      Haskell/Tools/Markup.hs
+    Author:     Makarius
+    LICENSE:    BSD 3-clause (Isabelle)
+
+Quasi-abstract markup elements.
+-}
+
+module Isabelle.Markup (T, empty, is_empty, Output, no_output)
+where
+
+import qualified Isabelle.Properties as Properties
+
+
+type T = (String, Properties.T)
+
+empty :: T
+empty = ("", [])
+
+is_empty :: T -> Bool
+is_empty ("", _) = True
+is_empty _ = False
+
+
+type Output = (String, String)
+
+no_output :: Output
+no_output = ("", "")