Rust - Json parser implementation in a functional way

The following git hub shows how Rust can implement Json parser by applying functional programming approach.

https://github.com/davidpdrsn/json-parser

Parer combinators which is related to this topic.
https://bodil.lol/parser-combinators/

Combine parser
https://github.com/Marwes/combine

It’s worth to mention nom too.
https://github.com/Geal/nom