promise?
tests whether the provided forms are promises
Usage:
(promise? form+) (!promise? form+)If all forms evaluate to a promise, then this function will return #t (true). The first non-promise will result in the function returning #f (false).
An Example
(define p1 (delay "one"))
(define p2 (delay "two"))
(promise? p1 p2 [1 2 3])
This example will return #f (false) because the third form is a vector.
Like most predicates, this function can also be negated by prepending the ! character. This means that all the provided forms must not be promises.
(!promise? "hello" [1 2 3])
This example will return #t (true).