Scheme's exception system is extended so that exception handlers
gain access to the delimited continuation representing the rest
of the computation of the call of the thunk guarded by the
handler. Algebraic effect handlers can be directly expressed in
this extended exception system. The system directly implements
the shift0/reset0 delimited control
operators. It is well known that other delimited control
operators like prompt0/control0 or
reset/shift are expressible
in shift0/reset0 (and vice versa).