When an exceptional situation is encountered by a program, it may
create a condition object describing the situation and then
signal the condition and pass control to a condition handler. The
signaler and handler are two different parts of a system, between which
there is a barrier of abstraction. In order to recover gracefully and
flexibly from exceptional situations, however, the signaler can provide
multiple ways by which the handler can restart the computation, some of
which may require extra input. Often, the decision of which method of
recovery to choose is left up to a human user, who may be prompted for
the input needed to recover. This SRFI proposes a simple mechanism
called restarters to encapsulate the information necessary to
restart a computation with associated interactive prompters.