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

(
#comment
(let config (DataSource 'config))
(let res_sink (DataSink 'result))

(let vt (VariantType (TupleType (DataType 'String) (DataType 'String) (DataType 'String))))
(let v0 (Variant (String 'aaa) '0 vt))
(let v1 (Variant (String 'bbb) '1 vt))
(let v2 (Variant (String 'ccc) '2 vt))
(let list (AsList v0 v1 v2))


(let inner (lambda '(list)
    (FlatMap list (lambda '(item)
        (Visit item
            '0 (lambda '(x) (OptionalIf (== x (String 'aaa)) (Variant (Concat (String '0-) x) '0 vt)))
            '1 (lambda '(x) (Just (Variant (Concat (String '1-) x) '1 vt)))
            (Just (Variant (String '2-) '2 vt))
        )
    ))
))

(let res (FlatMap (Apply inner (Iterator list (DependsOn (String 'a)))) (lambda '(item)
    (Just (VariantItem item))
)))
(let world (Write! world res_sink (Key) (Collect res) '('('type))))

(let res (FlatMap (Apply inner (Iterator list (DependsOn (String 'b)))) (lambda '(item)
    (Just (Visit item
            '0 (lambda '(x) (Variant x '0 vt))
            '1 (lambda '(x) (Variant x '1 vt))
            '2 (lambda '(x) (Variant x '1 vt))
    ))
)))
(let world (Write! world res_sink (Key) (Collect res) '('('type))))

(let res (FlatMap
    (FlatMap list (lambda '(item)
        (Visit item
            '0 (lambda '(x) (ListIf (== x (String 'aaa)) (Variant (Concat (String '0-) x) '0 vt)))
            '1 (lambda '(x) (AsList (Variant (Concat (String '1-) x) '1 vt) (Variant (Concat (String '2-) x) '2 vt)))
            (AsList (Variant (String '2-) '2 vt))
        )
    ))
    (lambda '(item)
        (Just (Visit item
                '0 (lambda '(x) (Variant x '0 vt))
                '1 (lambda '(x) (Variant x '1 vt))
                '2 (lambda '(x) (Variant x '1 vt))
        ))
    )
))
(let world (Write! world res_sink (Key) (Collect res) '('('type))))

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