Current Jam has a lot of bugs/limitations, both small (taking a sublist with an endpoint just doesn’t return anything) and fundamental (Jam doesn’t track it’s environment or Jamfiles so it can’t always tell when something needs to be rebuilt). It’s also generally a difficult codebase to work in.
Ham aims to be:
- Faster
- Usable as a library for IDEs
- More extensible
- Thoroughly tested
- Have better caching capabilities
It also has compatibility features that subsume other Jam forks, so it’s an all-in-one tool.