generated at
foldl1
from foldl

http://www.ndis.co.jp/blog/tech/2009/03/fold-2.html
http://zvon.org/other/haskell/Outputprelude/foldl1_f.html
https://blog.miz-ar.info/2019/10/scanl-and-scanr/
https://xtech.nikkei.com/it/article/COLUMN/20091009/338681/?P=4