how traditional iterative loops can be replaced with more concise and expressive functional expressions to achieve the same result in ABAP.

DATA itab TYPE STANDARD TABLE OF i WITH EMPTY KEY.
itab = VALUE #( FOR j = 1 WHILE j <= 10 ( j ) ).


* Old

DATA sum_old TYPE i.
DATA wa LIKE LINE OF itab.
LOOP AT itab INTO wa.
  sum_old = sum_old + wa.
ENDLOOP.

* New

DATA(sum_new) = REDUCE i( INIT x = 0
                          FOR <wa> IN itab
                          NEXT x = x + <wa> ).


ASSERT sum_old = sum_new.

cl_demo_output=>display( sum_new ).