Functional chart parsing of context-free grammars

This paper implements a simple and elegant version of bottom-up Kilbury chart parsing (Kilbury, 1985; Wiren, 4992). This is one of the many chart parsing variants, which are all based on the data structure of charts. The chart parsing process uses inference rules to add new edges to the chart, and parsing is complete when no further edges can be added. One novel aspect of this implementation is that it doesn't have to rely on a global state for the implementation of the chart. This makes the code clean, elegant and declarative, while still having the same space and time complexity as the standard imperative implementations.