ydb/yql/essentials/tests/s-expressions/suites/Builtins/Lookup.yql

(
#comment
(let mr_source (DataSource 'yt 'plato))
(let x (Read! world mr_source (Key '('table (String 'Input))) '('key 'subkey 'value) '()))
(let world (Left! x))
(let table1 (Right! x))
(let table1map (Map table1 (lambda '(item) (block '(
   (let value (Member item 'value))
   (let t1 (DataType 'Uint32))
   (let t2 (DataType 'String))
   (let d1 (DictType t1 t2))
   (let d2 (Dict d1 '((Uint32 '4) (String 'aaa)) '((Uint32 '5) (String 'bbb))) )
   (let newValue value)
   (let newValue (Concat newValue (String '" => ")))
   (let newValue (Concat newValue (Concat (String '" ") (Coalesce (Lookup d2 (Uint32 '4)) (String '?)))))
   (let newValue (Concat newValue (Concat (String '" ") (Coalesce (Lookup d2 (Uint32 '6)) (String '?)))))
   (let s (Struct))
   (let s (AddMember s 'key (Member item 'key)))
   (let s (AddMember s 'subkey (Member item 'subkey)))
   (let s (AddMember s 'value newValue))
   (return s)
)))))
(let mr_sink (DataSink 'yt (quote plato)))
(let world (Write! world mr_sink (Key '('table (String 'Output))) table1map '('('mode 'append))))
(let world (Commit! world mr_sink))
(return world)
)