List functions

lisp/kernel.gl

@@ -113,4 +113,4 @@ Spec is of the form (VARIABLE LIST &optional RETURN-FORM)."
   (princ datum print-char-fun)
   (terpri print-char-fun))
 
-(princln (nconc '(1 2) '(4 . 6) '(3 4)))
+(princln (append '(1 2) '(3 4)))

src/list.c

@@ -93,7 +93,30 @@ DEFUN(reverse, "reverse", (LispVal * list), "(list)", "") {
 }
 
 DEFUN(append, "append", (LispVal * lists), "(&rest lists)", "") {
-    return Qnil;
+    LispVal *out = Qnil;
+    LispVal *end = Qnil;
+    DOTAILS(rest, lists) {
+        LispVal *cur = XCAR(rest);
+        CHECK_LISTP(cur);
+        if (NILP(cur)) {
+            continue;
+        }
+        if (!NILP(XCDR(rest))) {
+            cur = Fcopy_list(cur);
+        }
+        if (NILP(out)) {
+            out = cur;
+        } else {
+            RPLACD(end, cur);
+        }
+        if (!NILP(XCDR(rest))) {
+            end = Flast(cur);
+            if (!NILP(XCDR(end))) {
+                signal_type_error(cur, Qlist);
+            }
+        }
+    }
+    return out;
 }
 
 DEFUN(nconc, "nconc", (LispVal * lists), "(&rest lists)", "") {