steel/meta
command-line
Returns the command line passed to this process, including the command name as first argument.
error-object-message
Returns the message of an error object.
(error-object-message error?) -> string?
make-weak-box
Allocates a weak box.
A weak box is similar to a box, but when the garbage collector can prove that the value of a weak box is only reachable through weak references, the weak box value will always return #false.
In other words, a weak box does not keep the value contained alive through a gc collection.
weak-box-value
Returns the value contained in the weak box. If the garbage collector has proven that the previous content value of weak-box was reachable only through a weak reference, then default-value (which defaults to #f) is returned.
(define value (make-weak-box 10))
(weak-box-value value) ;; => 10
(set! value #f) ;; Wipe out the previous value
(#%gc-collect)
(weak-box-value value) ;; => #false