Instaparse
A Clojure/ClojureScript parser generator that turns EBNF or ABNF grammars into executable parsers for any context-free grammar.
What is Instaparse?
Instaparse is a parser generator library for Clojure and ClojureScript that converts EBNF or ABNF grammar specifications into executable parsers. It solves the problem of building parsers for complex languages by providing a simple, notation-driven approach that works with any context-free grammar, including those with left recursion or ambiguity.
Clojure and ClojureScript developers who need to parse custom languages, data formats, or domain-specific languages without dealing with low-level parser implementation details.
Developers choose Instaparse because it eliminates the typical restrictions of parser generators, supports any context-free grammar, and integrates seamlessly with Clojure's data structures and transformation tools, making parsing as easy as writing a grammar.
Overview
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.
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