When comparing Chicken vs Gambit, the Slant community recommends Chicken for most people. In the question“What are the best scheme implementations?” Chicken is ranked 1st while Gambit is ranked 4th. The most important reason people chose Chicken is:
Chicken has easy to navigate and understand [documentation](http://wiki.call-cc.org/man/4/The%20User%27s%20Manual) that's updated frequently.
Ranked in these QuestionsQuestion Ranking
Pro Well documented
Chicken has easy to navigate and understand documentation that's updated frequently.
Pro Friendly, welcoming community
The Chicken community is very helpful and friendly.
Pro Easy to embed
Likewise, FFI is very simple compared to most Scheme implementations.
Pro Compiles to native code
Pro Permissive BSD License
It has a tool named chicken-doc. With its help you can easily add autocomplete and documentation features to your favorite editor.
Pro Good performance
Gambit is fast/efficient, you can see benchmarks here.
Pro Can be easily embedded into an existing C/C++ codebase
Gambit has a built-in compiler that generates C code, which then is passed to your system's compiler which in turn compiles it to native code. This makes it easy to integrate Gambit into existing C/C++ projects.
Pro Very portable
It is very portable as it has no external library dependencies. It will build as long as the platform has a C compiler.
Pro Actively maintained
Con Lacks proper UTF-8 support
For more detail see http://bugs.call-cc.org/ticket/1374
It's been up there for 9 months, still not fixed.
Con Lacks numeric tower support
The core system currently does not support the full numeric tower. However, there is an extension library available.
Con Lack of SRFIs
Gambit natively implements few SRFIs. Additional SRFIs are available through the Black Hole and Snow third-party systems.
Con Documentation is poorly formatted
The Gambit documentation directs you to further resources, depending on what you're looking for. Because things are separated into different places, it can be difficult to find what you need.
Some documentation is only available in HTML or PDF formats that are hard to read/follow.