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

(
# read data from Input table
(let config (DataSource 'config))

(let res_sink (DataSink 'result))

(let str1 (AsStruct '('a (Uint32 '1)) '('b (String 'a))))
(let str2 (AsStruct '('a (Uint32 '2)) '('b (String 'b))))
(let str3 (AsStruct '('a (Uint32 '3)) '('b (String 'c))))
(let list1 (AsList str1 str2))
(let list2 (AsList str2 str1))
(let list3 (AsList str1 str3))

(let cond (>= (RandomNumber) (Uint64 '0)))

(let res (FlatMap (OptionalIf cond str1) (lambda '(r) (OptionalIf (>= (Member r 'b) (String 'a)) r))))
(let world (Write! world res_sink (Key) res '('('type))))

(let res (FlatMap (OptionalIf cond str1) (lambda '(r) (AsList r r))))
(let world (Write! world res_sink (Key) res '('('type))))

(let res (FlatMap (OptionalIf cond str1) (lambda '(r) (ToStream (Just r) (DependsOn r)))))
(let world (Write! world res_sink (Key) (ForwardList res) '('('type))))

(let res (FlatMap (ListIf cond str1) (lambda '(r) (OptionalIf (>= (Member r 'b) (String 'a)) r))))
(let world (Write! world res_sink (Key) res '('('type))))

(let res (FlatMap (ListIf cond str1) (lambda '(r) (AsList r r))))
(let world (Write! world res_sink (Key) res '('('type))))

(let res (FlatMap (ListIf cond str1) (lambda '(r) (ToStream (Just r) (DependsOn r)))))
(let world (Write! world res_sink (Key) res '('('type))))

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