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Pros
Pro Guile is easy to start using for Bash, Python and C programmers
With Guile you can seamlessly program across languages such as Bash, Guile, C and Python. Simple scripts and programs that have started out as Bash-code can easily be extended in Guile when Bash is no longer sufficient by using the guile-bash library, and Guile itself can easily be extended in either C or Python (using the python-on-guile library) when Guile is no longer sufficient, e.g. due to performance or lack of libraries that accomplishes special tasks. Switching to Guile from either Bash, Python or C is therefore easy.
Cons
Con There aren't many other areas besides its major scope of interest
A true general purpose programming language is that with which anything can be done. That is not the case with guile, outside its major scope of interest, preferred scripting language for the GNU projects, the language is practically not used.