2.19 Continuation Marks: with-continuation-mark
(with-continuation-mark key-expr val-expr result-expr) |
The key-expr, mark-expr, and result-expr
expressions are evaluated in order. After key-expr is
evaluated to obtain a key and mark-expr is evaluated to
obtain a mark, the key is mapped to the mark in the current
continuation’s initial frame. If the frame already has a mark for the
key, it is replaced. Finally, the result-expr is evaluated;
the continuation for evaluating result-expr is the
continuation of the with-continuation-mark expression (so the
result of the result-expr is the result of the
with-continuation-mark expression, and result-expr
is in tail position for the with-continuation-mark
expression).
Continuation Marks provides more information on continuation marks.