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A monadic (I think...) recursive-descent parser written in Kotlin


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A monadic (I think...) recursive-descent parser combinator written in Kotlin

GitHub release (latest by date) Maven Central Kotlin Version

Kudzu is a recursive-descent parser written in Kotlin, inspired by Parsec, with the goal of immutability, simplicity, testability, and multiplatform usability. It's designed to be a simple starting place for writing smaller parsers to evaluate relatively simple grammars for other Copper-Leaf libraries, but flexible enough to be used for larger languages.

Notable features:

  • Multiplatform targets: JVM, Android, JS Legacy, JS IR, iOS
  • No separate lexer/parser. You really just don't need it, so Kudzu omits it
  • Parser combinator structure means every piece of your grammar is a complete parser, and thus smaller parsing units can be tested in isolation, but the combination of them creates the full language
  • Everything in Kudzu is immutable, and thus fully thread-safe
  • Built on top of DeepRecursiveFunction to provide readable stacktraces and prevent StackOverflowErrors
  • No complicated DSL or arcane combinator operators required, just normal, readable Kotlin classes. You don't need a Ph.D. in computational linguistics or functional programming to understand a Kudzu parser
  • Many useful combinators provided out of the box
    • Boolean, Int, Double literals
    • String and Character literals, with standard escaped characters (i.e. \n) and Unicode sequences (i.e. \u00A2)
    • Identifiers
    • Choice, repetition, optional higher-kinded parsers
  • Parses input to an Abstract Syntax Tree (AST) and provides facilities for simplifying and/or introspecting the AST
  • Line- and column-number source tracking
  • Generic expression parser with all the fixin's
    • Customizable operator precedence
    • Operators with prefix, postfix, and infix with both left- and right-recursive associativity
    • Parentheses
    • Simplify deeply-nested expressions AST to simpler representation

Supported Platforms/Features



repositories {

// for plain JVM or Android projects
dependencies {

// for multiplatform projects
kotlin {
    sourceSets {
        val commonMain by getting {
            dependencies {


See the website for detailed documentation and usage instructions.


Kudzu is licensed under the BSD 3-Clause License, see