Five programs that copy or delete a whole directory tree, however deep it
goes, on a calculator whose entire file system is a variable list. There is no
path type, no recursion primitive and no way to ask what kind of thing a name
holds. Watch what they use instead: a list turned into text and back, and an
error message read as an answer.
CPYDR and DELDR are the only programs in the notebook that call themselves.
The recursion is the part I still remember enjoying, the only thing about them
that survived thirty-seven years. The question inked on the page is about the
recursion too.
The listing
The variable tree
running
Space or → steps · Enter runs to the next note.
Underlined tokens have something to say. The highlighted line of the tree is
the current directory.