Add map functions (map, map_keys, map_values, map_extract, map_entries, element_at)

[timsaucer]

Summary

The upstream DataFusion library provides map functions that are not yet exposed in datafusion-python. These are needed for working with map/dictionary data types.

Missing Functions

• map — creates a map from key/value arrays
• map_entries — returns entries of a map as an array of structs
• map_extract — extracts value by key from a map
• map_keys — returns all keys of a map
• map_values — returns all values of a map
• element_at — access element in a map or array by key/index

Upstream Reference

• https://datafusion.apache.org/user-guide/sql/scalar_functions.html (Map Functions section)

Implementation

• Rust bindings: crates/core/src/functions.rs
• Python wrappers: python/datafusion/functions.py

Note: This gap analysis was performed using an AI agent comparing upstream DataFusion v53 documentation against the current datafusion-python codebase.