X.FDATATYPES is a Common Lisp library which implements 3 functional data structures:
- hash-table
- array
- set

Implementation is based on Clojure's variation of Bagwell Tries, 
API is different.

X.FDATATYPES also implements FMAP, FOLD, FILTER and FMAP-TO functions for easy working 
with data structures. 

X.FDATATYPES does not try to behave as common CL data structures, and therefore function
names in the package are intentionally different than the ones found in CL.

More functional data structures will be introduced as the need arises.