Lazy functional incremental parsing

Structured documents are commonly edited using a free-form editor. Even though every string is an acceptable input, it makes sense to maintain a structured representation of the edited document. The structured representation has a number of uses: structural navigation (and optional structural editing), structure highlighting, etc. The construction of the structure must be done incrementally to be efficient: the time to process an edit operation should be proportional to the size of the change, and (ideally) independent of the total size of the document. We show that combining lazy evaluation and caching of intermediate (partial) results enables incremental parsing. We build a complete incremental parsing library for interactive systems with support for error-correction.