- (check-arg predicate? expr [caller])syntax
Guarantees that the expression expr satisfies the procedure predicate?. Implementations can enforce the predicate check in all the code that follows, but are not required to. An error is raised if the predicate returns #f when called on the value that expr evaluates to. Otherwise, return value is unspecified.
Note that check-arg will do nothing if you compile your program with the -unsafe flag, as this macro expands to call CHICKEN's assert internally.