duckling

Instaparse

Instaparse is a parser generator for Clojure and ClojureScript that transforms standard EBNF or ABNF notation into executable parsers. It aims to make context-free grammars as easy to use as regular expressions, providing a simple yet powerful way to build parsers for a wide range of languages and data formats. ## Key Features - **Any Context-Free Grammar** — Works for left-recursive, right-recursive, and ambiguous grammars without restrictions. - **PEG Extensions** — Adds lookahead, negative lookahead, and ordered choice operators for enhanced expressiveness. - **Flexible Output Formats** — Supports both hiccup and enlive tree formats for easy manipulation in Clojure. - **Detailed Error Reporting** — Provides clear parse error messages and supports total parse mode for debugging. - **Combinator Library** — Optional programmatic grammar construction alongside string-based specifications. - **Partial Parsing** — Allows parsing of initial portions of input strings for incremental processing. ## Philosophy Instaparse believes that writing parsers should be straightforward and accessible, leveraging familiar notation while removing traditional limitations like grammar restrictions or left-recursion issues.