.. _stdlib:predefined-exceptions:

Predefined exceptions in the standard library
=============================================

ABS provides predefined exceptions that are thrown in specific
circumstances.  See :ref:`sec:exception-types` for information about
exceptions.

.. note:: This list is subject to revision in future versions of ABS.
          Not all these exceptions are currently thrown by different
          backends in the described situation.

``DivisionByZeroException``

    Raised in arithmetic expressions when the divisor (denominator) is
    equal to 0, as in +3/0+

``AssertionFailException``

    The assert statement was called with an argument that evaluated to
    ``False``.

``PatternMatchFailException``

    A value did not match any pattern in a pattern-matching
    expression.

``NullPointerException``

    A method was called on ``null``, or ``await`` or ``get`` were
    passed a null future.

``StackOverflowException``

    The calling stack has reached its limit (system error)

``HeapOverflowException``

    The memory heap is full (system error)

``KeyboardInterruptException``

    The user pressed a key sequence to interrupt the running ABS
    program

``ObjectDeadException``

    A method was called on a dead (crashed) object