When comparing Guile vs CMUCL, the Slant community recommends Guile for most people. In the question“What are the best Lisp dialects?” Guile is ranked 4th while CMUCL is ranked 13th. The most important reason people chose Guile is:
Guile makes it easy for users of your application to write extensions without needing to understand the plumbing of your program.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Easy to customize and extend applications
Guile makes it easy for users of your application to write extensions without needing to understand the plumbing of your program.
Pro GNU's official extension language
Chances are a system running enough GNU software will already have it installed.
Pro Excellent documentation
The documentation provides conceptual overviews, tutorials, and a detailed reference for all commands, functions, and operators.
Pro Fantastic interface to C, C++ in both directions, embedding guile in C/C++ and embedding C/C++ in guile
Pro Fast execution, faster compilation
CMUCL runs about as fast as SBCL, and they are both among the fastest Common Lisp implementations. CMUCL compiles faster than SBCL, cutting down on development, deployment, installation, and user testing turnaround time.
Pro Stand-alone executables
Pro Copyfree licensed (revised BSD license)
Most of CMUCL is in the public domain, with a few subsytems under permissive license.
Cons
Con Weak copyleft
LGPL