I'm generally an advocate for a robust, mandatory type system like Rust. But there are production scenarios where it's a hindrance. Imagine processing arbitrary

I'm generally an advocate for a robust, mandatory type system like Rust. But there are production scenarios where it's a hindrance. Imagine processing arbitrary JSON document containing several required properties and many additional ones. You can't possibly know what additional properties any given document will have (it's only available at runtime, with infinite variations) but it's often a hard requirement that these extra data get passed through the system. Being forced to create a concrete type for what is effectively an open map + some validation logic is awkward at best. Maps and general purpose functions that process maps are a better fit for this problem.