Engelberg/instaparse

Health v2 · maintenance only

Flags: no_releases

Adoption not part of the score

2822 stars · 153 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Instaparse is a Clojure/ClojureScript library that turns context-free grammars written in standard EBNF or ABNF notation into executable parsers that map input strings to parse trees. It handles any context-free grammar, including left-recursive and ambiguous ones, and offers hiccup/enlive output, lookahead extensions, full parse enumeration, and detailed error reporting.

Use cases

• parse strings with a context-free grammar in Clojure
• turn an EBNF or ABNF grammar into a working parser
• build a parser for a small DSL without hand-writing a lexer
• handle left-recursive or ambiguous grammars and enumerate all parses
• debug a grammar that fails to match a string
• produce parse trees in hiccup or enlive format
• extend a grammar with lookahead and negative lookahead

When to choose

• You want to go from a written grammar to an executable parser with almost no boilerplate in Clojure or ClojureScript
• Your grammar is left-recursive, ambiguous, or otherwise hard for hand-rolled or LL/LR tools to handle
• You need to inspect all possible parses while designing or debugging a grammar
• You prefer declarative EBNF/ABNF notation over building parsers combinator by combinator

When to avoid

• You need a hand-tuned lexer/parser generator for maximum throughput on very large inputs
• You require strict PEG semantics or streaming/incremental parsing
• You are working outside Clojure/ClojureScript (JVM or JavaScript runtimes)
• Regular expressions are sufficient for your pattern-matching needs

Facets

library · maturity stable

parser parsers programming-languages developer-tools jvm browser clojure clojurescript context-free-grammar ebnf abnf parser-combinator parse-tree parser-generator peg-lookahead ambiguous-grammars dsl-parsing nodejs

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