`error'
-------

error(MESSAGE)
     :: Forces Asir to cause an error and enter debugging mode.

MESSAGE
     string

   * When Asir encounters a serious error such that it finds difficult
     to continue execution, it, in general, tries to enter debugging
     mode before it returns to top level.  The command `error()' forces
     a similar behavior in a user program.

   * The argument is a string which will be displayed when `error()'
     will be executed.

   * You can enter the debug-mode when your program encounters an
     illegal value for a program variable, if you have written the
     program so as to call `error()' upon finding such an error in your
     program text.

     % cat mod3
     def mod3(A) {
             if ( type(A) >= 2 )
                     error("invalid argument");
             else
                     return A % 3;
     }
     end$
     % asir
     [0] load("mod3");
     1
     [3] mod3(5);
     2
     [4] mod3(x);
     invalid argument
     stopped in mod3 at line 3 in file "./mod3"
     3                       error("invalid argument");
     (debug) print A
     A = x
     (debug) quit
     return to toplevel
     [4]

References
     *Note `debug': debug.

