--- slib/srfi-1.scm	2008-12-08 03:29:50.000000000 +0100
+++ slib/srfi-1.scm	2012-10-31 14:43:00.932721359 +0100
@@ -234,6 +234,13 @@
       z
       (apply fold (cons* f (apply f (append! (map car l) (list z)))
 			 (map cdr l)))))
+
+(define (fold-left f z l1 . l)
+  (set! l (cons l1 l))
+  (if (any null? l)
+      z
+      (apply fold-left (cons* f (apply f (cons z (map car l)))
+			 (map cdr l)))))
 ;;@args kons knil clist1 clist2 ...
 (define (fold-right f z l1 . l)
   (set! l (cons l1 l))
@@ -247,6 +254,18 @@
       z
       (let ((tail (cdr l)))
 	(pair-fold f (f l z) tail))))
+; good pair-fold-left now
+(define (pair-fold-left f z l)		;XXX should be multi-arg
+   (let rec ((lis l)
+	     (rlis #f)
+	     (last #f)
+	     (ans z))
+      (if (null? lis)
+	  ans
+	  (let ((new (list (car lis))))
+	     (if last (set-cdr! last new) (set! rlis new))
+	     (rec (cdr lis) rlis new (f ans rlis))))
+      ))
 ;;@args kons knil clist1 clist2 ...
 (define (pair-fold-right f z l)		;XXX should be multi-arg
   (if (null? l)
@@ -264,6 +283,17 @@
 		       ridentity
 		       (fold f (car list) (cdr list)))))
 	     args))))
+
+(define reduce-left
+  (let ((comlist-reduce reduce-left))
+    (lambda args
+      (apply (if (= 2 (length args))
+		 comlist-reduce
+		 (lambda (f ridentity list)
+		   (if (null? list)
+		       ridentity
+		       (fold-left f (car list) (cdr list)))))
+	     args))))
       
 (define (reduce-right f ridentity list)
   (if (null? list)