Anatomy of verl, the RL post-training framework I lived in

I came to verl for a research project: RL on function calling. I needed custom environments where the model interacts with tools and is rewarded on the call it makes. The capability to have custom rewards and eventually the room to modify or write the algorithms. Also, since I was familiar with them, I wanted FSDP and vLLM if I could get them. Oh, and not to forget, the capability to do long…