David Kastrup <d...@gnu.org> writes: > The following code results in an error: > > (use-modules (srfi srfi-1)) > (reduce-right + 0 (make-list 10000 1))
[...] > srfi/srfi-1.scm:379:31: In procedure recur: > srfi/srfi-1.scm:379:31: Throw to key `vm-error' with args `(vm-run "VM: Stack > overflow" ())'. Yes, this should be fixed. > It turns out that the call of drop-right is responsible here: > > (define (drop-right lis k) > (let recur ((lag lis) (lead (drop lis k))) > (if (pair? lead) > (cons (car lag) (recur (cdr lag) (cdr lead))) > '()))) Thanks for tracking this down. > For all the cleverness involved here, one has to run through the whole > list anyway. It makes no real sense to do this in this manner. The > motivation may be to have a warm cache when k is small, but the result > is self-defeating because of VM stack buildup. > > (define (drop-right lis k) > (drop lis (- (length lis) k))) > > should be all that is needed. That won't be sufficient. SRFI-1 specifies that 'drop-right' works for dotted lists, i.e. finite non-nil-terminated lists, whereas 'length' accepts only proper lists. It includes these examples: (drop-right '(1 2 3 . d) 2) => (1) (drop-right '(1 2 3 . d) 0) => (1 2 3) See <http://srfi.schemers.org/srfi-1/srfi-1.html>. Would you like to propose another fix? Thanks, Mark
