[DISCUSS] Support Higher-order functions
Spark 2.4.0 was released last month. I noticed that Spark sql in Spark 2.4 adds a lot of higher-order functions, to deal with complex data types easier.
For example, SQL statement like "SELECT TRANSFORM(values, element -> element + 1) FROM iteblog;" returns an array that is the result of applying function to each element of array.
I wonder if it is possible for Calcite to enhance it's parser to support higher-order functions. Thus, projects powered by Calcite such as Flink can benefit from it.
Look forward to your feedback.