CAR and CDR work for NIL object

diff --git a/lispstrack.lisp b/lispstrack.lisp
index 59e1c85..94f5a37 100644 (file)
--- a/lispstrack.lisp
+++ b/lispstrack.lisp
@@ -509,10 +509,16 @@
            "; return (typeof tmp == 'object' && 'car' in tmp);})()")))
 
 (define-compilation car (x)
-  (concat "(" (ls-compile x env fenv) ").car"))
+  (concat "(function () { var tmp = " (ls-compile x env fenv)
+          "; return tmp === " (ls-compile nil nil nil) "? "
+          (ls-compile nil nil nil)
+          ": tmp.car; })()"))
 
 (define-compilation cdr (x)
-  (concat "(" (ls-compile x env fenv) ").cdr"))
+  (concat "(function () { var tmp = " (ls-compile x env fenv)
+          "; return tmp === " (ls-compile nil nil nil) "? "
+          (ls-compile nil nil nil)
+          ": tmp.cdr; })()"))
 
 (define-compilation setcar (x new)
   (concat "((" (ls-compile x env fenv) ").car = " (ls-compile new env fenv) ")"))

diff --git a/test.lisp b/test.lisp
index d4ff11f..7652409 100644 (file)
--- a/test.lisp
+++ b/test.lisp
@@ -837,10 +837,16 @@ c(defmacro eval-when-compile (&body body)
            "; return (typeof tmp == 'object' && 'car' in tmp);})()")))
 
 (define-compilation car (x)
-  (concat "(" (ls-compile x env fenv) ").car"))
+  (concat "(function () { var tmp = " (ls-compile x env fenv)
+          "; return tmp === " (ls-compile nil nil nil) "? "
+          (ls-compile nil nil nil)
+          ": tmp.car; })()"))
 
 (define-compilation cdr (x)
-  (concat "(" (ls-compile x env fenv) ").cdr"))
+  (concat "(function () { var tmp = " (ls-compile x env fenv)
+          "; return tmp === " (ls-compile nil nil nil) "? "
+          (ls-compile nil nil nil)
+          ": tmp.cdr; })()"))
 
 (define-compilation setcar (x new)
   (concat "((" (ls-compile x env fenv) ").car = " (ls-compile new env fenv) ")"))