Joe Marshall discusses fold-left and fold-right here:

http://funcall.blogspot.com/2021/08/fold-right.html

His post has raised questions in my mind about whether SRFI 179 defines
array-fold, array-fold-right, and array-reduce in The Right Way (TM).  I
added a comment that notes:

heine:~/programs/gambit/gambit> gsi
Gambit v4.9.3-1503-gd1a6c6bf

 > (import (srfi 179))
 > (define a (make-array (make-interval '#(2 2))
                       (lambda (i j)
                         (string->symbol (string-append "a_"
(number->string i) (number->string j))))))
 > (array-fold (lambda (l r) `(f ,l ,r)) 'init a)
(f a_11 (f a_10 (f a_01 (f a_00 init))))
 > (array-fold-right (lambda (l r) `(f ,l ,r)) 'init a)
(f a_00 (f a_01 (f a_10 (f a_11 init))))
 > (array-reduce (lambda (l r) `(f ,l ,r)) a)
(f (f (f a_00 a_01) a_10) a_11)

These functions work the way they're documented, so I don't think any
errata need to be applied to SRFI 179, but I'm wondering if this is
another small thing that should be changed in a follow-up SRFI.

Brad