Through its robustness, performance, extensive debugging features, clustering functionality, expert community, and through being open source, Gambit Scheme http://www.iro.umontreal.ca/~gambit/
is certainly a very strong candidate. An extensive module system is underway, easing incremental development processes for large projects.
is interesting by being one of the industry's most sophisticated incremental compilers. It has very high potential upside in performance, though may not score highest in debuggability features. The commercial analogue to Ikarus is Chez Scheme http://www.scheme.com/
is interesting through being a small interpreter environment.
is interesting through generating small binaries.
is interesting through providing a complete R5RS Scheme environment atop Java.
Scheme generally signifies itself by its many high quality implementations, including Chicken http://www.call-with-current-continuation.org/
, PLT http://plt-scheme.org/
, MIT http://groups.csail.mit.edu/mac/projects/scheme/
, Gauche http://practical-scheme.net/gauche/
, and many others, as well.
In terms of pre-built libraries, it may be that PLT and Chicken score the highest. Though, like when planning any technology project, you need to ask yourself what libraries are relevant to you, and what purpose they should fill, in detail.
Generally speaking, Scheme implementations differentiate themselves through
- how they do threading (green threading, operating system threads such as pthreads, none, mixed)
- if they fully support continuations
- how R5RS and/or R6RS compliant they are
- how performant they are
- how robust they are
- what debuggability features they have
- how deep operating system integration they have, and for what operating systems
Scheme has the world's highest number of high-quality software development environments for one and the same programming language.