diff options
Diffstat (limited to 'chess-polyglot.el')
| -rw-r--r-- | chess-polyglot.el | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/chess-polyglot.el b/chess-polyglot.el index af1767b..391320d 100644 --- a/chess-polyglot.el +++ b/chess-polyglot.el @@ -508,15 +508,16 @@ distribute the probability that a move gets picked." (cl-flet ((ply-weight (ply) (round (expt (chess-ply-keyword ply :polyglot-book-weight) strength)))) - (let* ((plies (chess-polyglot-book-plies book position)) - (random-value (random (cl-reduce #'+ (mapcar #'ply-weight plies)))) - (max 0) ply) - (while plies - (if (< random-value (cl-incf max (ply-weight (car plies)))) - (setq ply (car plies) plies nil) - (setq plies (cdr plies)))) - (cl-assert ply) - ply))) + (let ((plies (chess-polyglot-book-plies book position))) + (when plies + (let ((random-value (random (cl-reduce #'+ (mapcar #'ply-weight plies)))) + (max 0) ply) + (while plies + (if (< random-value (cl-incf max (ply-weight (car plies)))) + (setq ply (car plies) plies nil) + (setq plies (cdr plies)))) + (cl-assert ply) + ply))))) (defalias 'chess-polyglot-book-close 'kill-buffer "Close a polyglot book.") |