[brudgers]

When in doubt, use brute force. -- Ken Thompson

Using hashes as a first choice data structure is not necessarily a bad idea. 1] Until profiling a working implementation demonstrates otherwise, other data structures may be premature optimization.

[1] Clearly an improvement over the Lisper's association lists.

[Grue3]

It's not an improvement over small association lists. At least in Common Lisp hashes are pretty heavy and assoc lists will outperform them if there are less than ~100 elements.