The non-local flow of control caused by continuations might sometimes
not be wanted. You can use
with-continuation-barrier to erect
fences that continuations can not pass.
Call proc and return its result. Do not allow the invocation of
continuations that would leave or enter the dynamic extent of the call
with-continuation-barrier. Such an attempt causes an error
to be signaled.
Throws (such as errors) that are not caught from within proc are
with-continuation-barrier. In that case, a short
message is printed to the current error port and
#f is returned.
with-continuation-barrier returns exactly once.
scm_with_continuation_barrier but call func on
data. When an error is caught,
NULL is returned.