1.1 --- a/src/Tools/isac/ProgLang/Prog_Expr.thy	Sun Sep 12 15:53:36 2021 +0200
     1.2 +++ b/src/Tools/isac/ProgLang/Prog_Expr.thy	Sun Sep 12 16:18:03 2021 +0200
     1.3 @@ -439,7 +439,7 @@
     1.4  (*("argument_in" ,("Prog_Expr.argument_in", Prog_Expr.eval_argument_in "Prog_Expr.argument_in"))*)
     1.5  fun eval_argument_in _ "Prog_Expr.argument_in" 
     1.6  		 (t as (Const ("Prog_Expr.argument_in", _) $ (_(*f*) $ arg))) _ =
     1.7 -    if is_Free arg (*could be something to be simplified before*)
     1.8 +    if TermC.is_atom arg (*could be something to be simplified before*)
     1.9      then
    1.10        SOME (UnparseC.term t ^ " = " ^ UnparseC.term arg,
    1.11  	      HOLogic.Trueprop $ (TermC.mk_equality (t, arg)))