ydb/yql/essentials/tests/s-expressions/suites/Optimizers/ConsumeOrMoveForwardList.yqls

(
(let config (DataSource 'config))

(import id_module '"/lib/yql/id.yql")
(let id (bind id_module 'id))

(let list (AsList (String 'a) (String 'b) (String 'c)))

(let res_sink (DataSink 'result))
(let world (Write! world res_sink (Key) (ForwardList (Iterator list (DependsOn (Int32 '0)))) '('('type))))
(let world (Write! world res_sink (Key) (ForwardList (Apply id (Iterator list (DependsOn (Int32 '1))))) '('('type))))
(let world (Write! world res_sink (Key) (Fold (ForwardList (Apply id (Iterator list (DependsOn (Int32 '2))))) (String '"") 
  (lambda '(item state) (Concat item state))) '('('type))))
(let world (Write! world res_sink (Key) (Fold1 (ForwardList (Apply id (Iterator list (DependsOn (Int32 '3))))) 
  (lambda '(item) item)
  (lambda '(item state) (Concat item state))) '('('type))))
(let world (Write! world res_sink (Key) (FlatMap (ForwardList (Apply id (Iterator list (DependsOn (Int32 '4)))))
  (lambda '(item) (AsList item item))) '('('type))))
(let world (Write! world res_sink (Key) (FoldMap (ForwardList (Apply id (Iterator list (DependsOn (Int32 '5))))) (String '"") 
  (lambda '(item state) '((Concat item state) (Concat item state)))) '('('type))))
  
(let world (Write! world res_sink (Key) (Fold1Map (ForwardList (Apply id (Iterator list (DependsOn (Int32 '6))))) 
  (lambda '(item) '(item item))
  (lambda '(item state) '((Concat item state) (Concat item state)))) '('('type))))  

(let world (Commit! world res_sink))
(return world)

)