first-time-value returns the result of evaluating a form
in the current lexical and dynamic context the first time it's encountered,
and the cached result of that computation on subsequent evaluations.
Simply import first-time-value (and possibly also first-time-values) for normal usage. Don't (:use)!
This package will be mostly designed for explicit qualification of symbols if it ever exports more symbols, such as first-time-value:foo.
form => object
On first evaluation, first-time-value attempts to evaluate form in the current lexical and dynamic context and cache the primary value it returns, and return that value.
If form performed a non-local exit, then the next evaluation of this first-time-value call will perform the aforementioned steps again.
On subsequent evaluations after a successful evaluation of form, first-time-value ignores form and returns the value that was previously cached.
first-time-value is similar to load-time-value, but evaluates its form in the current lexical and dynamic environment instead of in a null environment, and at the time that code at that location would normally be executed instead of at load time.
form => object*
Like first-time-value, except that all values returned from form are cached and returned instead of only the primary value.
(first-time-values form) == (values-list (first-time-value (multiple-value-list form)))