Similar to the Chandler PIM, the Haystack system unifies handling different types of unstructured information. This information has a common representation in RDF that is presented to users in a configurable human-readable way.
Haystack was developed in the RDF-aware dynamic language Adenine which was created for the project. The language was named after the nucleobase adenine and is a scripting language that is cross-platform. It is the perhaps the earliest example of a homoiconic general graph (rather than list/tree) programming language.
A substantial characteristic of Adenine is that this language possesses native support for the Resource Description Framework (RDF). The language constructs of Adenine are derived from Python and Lisp. Adenine is written in RDF and thus also can be represented and written with RDF based syntaxes such as Notation3 (N3).
^Karger, David R.; Dennis Quan (2004). "Haystack: a user interface for creating, browsing, and organizing arbitrary semistructured information". CHI '04 extended abstracts on Human factors in computing systems. Vienna, Austria: ACM. pp. 777–778. ISBN1-58113-703-6.