!253 improve rich-vector%zip-with-index

GoldfishLang.tmu

@@ -5388,21 +5388,27 @@
   <\goldfish-chunk|goldfish/liii/lang.scm|true|true>
     (chained-define (%zip-with-index)
 
-    \ \ (chained-define (loop lst idx save)
+    \ \ (let* ((n (vector-length data))
 
-    \ \ \ \ (if (null? lst)
+    \ \ \ \ \ \ \ \ \ (result (make-vector n)))
 
-    \ \ \ \ \ \ \ \ (reverse (list-\<gtr\>vector save)) \ 
+    \ \ \ \ (let loop ((idx 0))
 
-    \ \ \ \ \ \ \ \ (loop (cdr lst)\ 
+    \ \ \ \ \ \ (if (\<gtr\>= idx n)
 
-    \ \ \ \ \ \ \ \ \ \ \ \ \ \ (+ idx 1)\ 
+    \ \ \ \ \ \ \ \ \ \ (rich-vector result)
 
-    \ \ \ \ \ \ \ \ \ \ \ \ \ \ (cons (cons idx (car lst)) save))))
+    \ \ \ \ \ \ \ \ \ \ (begin
 
-    \;
+    \ \ \ \ \ \ \ \ \ \ \ \ (vector-set!\ 
+
+    \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ result\ 
+
+    \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ idx\ 
+
+    \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ (cons idx (vector-ref data idx)))
 
-    \ \ (rich-vector (loop (vector-\<gtr\>list data) 0 '())))
+    \ \ \ \ \ \ \ \ \ \ \ \ (loop (+ idx 1)))))))
 
     \;
   </goldfish-chunk>

goldfish/liii/lang.scm

@@ -1121,14 +1121,17 @@
     (rich-hash-table group)))
 
 (chained-define (%zip-with-index)
-  (chained-define (loop lst idx save)
-    (if (null? lst)
-        (reverse (list->vector save))  
-        (loop (cdr lst) 
-              (+ idx 1) 
-              (cons (cons idx (car lst)) save))))
-
-  (rich-vector (loop (vector->list data) 0 '())))
+  (let* ((n (vector-length data))
+         (result (make-vector n)))
+    (let loop ((idx 0))
+      (if (>= idx n)
+          (rich-vector result)
+          (begin
+            (vector-set! 
+                result 
+                idx 
+                (cons idx (vector-ref data idx)))
+            (loop (+ idx 1)))))))
 
 (chained-define (%distinct)
   (let ((ht (make-hash-table))