diff options
Diffstat (limited to 'share')
| -rw-r--r-- | share/txr/stdlib/place.tl | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/share/txr/stdlib/place.tl b/share/txr/stdlib/place.tl index 7ef7f44d..5d17acb7 100644 --- a/share/txr/stdlib/place.tl +++ b/share/txr/stdlib/place.tl @@ -295,6 +295,19 @@ (with-delete-expander (deleter) place env ^(,deleter))) +(defmacro lset (. places-source) + (let ((places (butlast places-source)) + (source (last places-source)) + (orig (gensym)) + (iter (gensym))) + (unless places + (sys:eval-err "lset: require one or more places followed by expression")) + ^(let* ((,orig ,(car source)) + (,iter ,orig)) + ,*(butlast (mappend (ret ^((set ,@1 (car ,iter)) (set ,iter (cdr ,iter)))) + places)) + ,orig))) + (defmacro defplace (place-destructuring-args body-sym (getter-sym setter-sym update-body) : ((ssetter-sym clobber-body)) |