It's supposed to be a predicate for a non-nil atom. I just realize that could better be written as (~acons current) instead, given that (acons nil) is also nil.
I was confused because (~no current) is just the same as current by itself, and I didn't realize you wanted to test for non-nil atoms. Obviously (~no current) isn't what you want, because it returns true for lists.
arc> (~no nil)
nil
arc> (~no 'a)
t
arc> (~no '(1 2 3))
t
But I don't think (~acons current) does what you want either. Because (acons nil) is nil, (~acons nil) is true.
arc> (~acons nil)
t
arc> (~acons 'a)
t
arc> (~acons '(1 2 3))
nil
I think (~alist current) returns true for non-nil atoms, because (alist nil) is true.
