On the subject of yaml I like the not so well known approach taken by Python library strictyaml: <https://github.com/crdoconnor/strictyaml>
Basically they remove a lot of yaml functionality (including type inference). What is left is a very simple format that I think is one of the best way to provide manually generate data for complex configurations (while json is best for machine generated data, and toml better for simple configuration). An interesting library that goes in this direction (simplifying yaml) is nyml by @georgelemon: <https://github.com/openpeep/nyml>
