Dictionary of Algorithms and Data Structures
http://www.itl.nist.gov/div897/sqg/dads/terms.html

Definitions of algorithms, data structures, and classical Computer Science problems. Some entries have links to implementations and more information.

What finger trees do is give me a way of representing a list that has both the convenience of the traditional cons list, and the search efficiency of the array based method. The basic idea of the finger tree is amazingly simple. It's a balanced tree where you store all of the data in the leaves. The internal nodes are just a structure on which you can hang annotations, which you can use for optimizing search operations on the tree.

"The basic idea of the finger tree is amazingly simple. It's a balanced tree where you store all of the data in the leaves. The internal nodes are just a structure on which you can hang annotations, which you can use for optimizing search operations on the tree. What makes the finger tree so elegant is the way that some very smart people have generalized the idea of annotations to make finger trees into a single, easily customizable structure that's useful for so many different purposes: you customize the annotations that you're going to store in the internal nodes according to the main use of your tree." A commentator says regarding the article however, "Ørjan Johanse is right. You described a monoid-annotated-binary-tree, which is not enough to be a finger tree."