TRY-EXCEPT Statement

TRY
  <guarded stmts>
EXCEPT
"|" <exception id> { "," <exception id> ... } "=>" <stmts>
    (* Non-parameterized exceptions *)

"|" <exception id> "(" <parm id> ")" "=>" <stmts>
    (* Parameterized exception handler *)

[ ELSE <stmts> ]
END

The TRY-EXCEPT statement guards statements between TRY and EXCEPT with the exception handlers between EXCEPT and END. An exception raised by a <guarded stmt> is handled by <stmts> in the corresponding handler, or by ELSE <stmts>, if present, and execution continues with the statement following END.

EXCEPTION Failure(Severity);
TYPE Severity = {Low, Medium, High};
...

TRY
  ...
EXCEPT
| IO.Error =>
    IO.Put("An I/O error occurred.")
| Lex.Error =>
    IO.Put("Unable to convert datatype.")
| Severity(x) => 
    IF x = Severity.Low THEN IO.Put("Not bad") ELSE IO.Put("Bail out") END
END;