Extention Module/ list of chars-> string

[Tuvas]

I am currently writing an extention module that needs to recieve a list
of characters that might vary in size from 0 to 8. This is written as a
list of characters rather than a string because it's easier to
manipulate. However, when I pass this list of characters into the
extention module, it keeps giving errors. Is there a way to do one of
the following?

A. Change a list of chars to a single string or
B. Read a list of chars in an extention module

Thanks!