Hi Blake, thanks for your reply.
I actually don't need to convert to ASCII -- what I really want to do is to call a Java method which has a char argument. I got the following error:
CL-USER(19): (jss:new "org.armedbear.lisp.LispCharacter" #\U2502) #<THREAD "interpreter" native {41BFB5BC}>: Debugger invoked on condition of type JAVA-EXCEPTION Java exception 'java.lang.NoSuchMethodException: LispCharacter(java.lang.Character)'.
It appears that the Lisp character #\U2502 has been converted to a Java Character, but that's not acceptable to the org.armedbear.lisp.LispCharacter constructor, which is declared to take a char argument; see line 70 of src/org/armedbear/lisp/LispCharacter.java in the current version (commit bba779e).
Now a complicating factor is that the LispCharacter(char) constructor is declared private -- I don't know if that's the actual problem, and the error message about the argument type is misleading. Are Java private methods, variables, and constructors visible from Lisp?
All the best,
Robert