Automat
A Clojure/ClojureScript library for building and using finite-state automata through functional composition.
What is Automat?
Automat is a library for creating and using finite-state automata in Clojure and ClojureScript through functional composition. It solves the problem of defining complex state machines without a custom DSL, offering high performance and seamless integration with Clojure's functional paradigms.
Clojure and ClojureScript developers who need to implement finite-state machines for tasks like parsing, stream processing, or behavioral tracking.
Developers choose Automat for its blend of Ragel-like power with Clojure's composability, enabling fast, declarative automata that are easy to extend and visualize.
Overview
better automata through combinators
Use Cases
Best For
- Parsing and validating sequences of inputs in Clojure applications
- Implementing high-performance stream processing with stateful reduction
- Tracking user behavior patterns in web applications (e.g., e-commerce flows)
- Building composable, declarative automata for protocol or format validation
- Creating reusable FSM components for complex event-driven logic
- Precompiling automata in Clojure for use in ClojureScript to optimize startup time
Not Ideal For
- Projects that don't involve sequence processing or state-based logic, as Automat is specifically designed for finite-state automata
- Teams needing a drag-and-drop GUI for FSM design, since visualization is code-based and Clojure-only
- Real-time systems requiring asynchronous event handling, as Automat processes inputs synchronously in streams
- Environments where Clojure is not an option, limiting use to JVM and JavaScript runtimes
Pros & Cons
Pros
Allows building automata using pure functions and combinators like `or`, `and`, `*`, making it declarative and easy to extend, as shown in the README examples with interposed patterns.
Compiled automata process 100 million elements in 500ms with mean transition times of 5ns, optimized for speed in high-throughput use cases.
The `$` operator enables attaching reducer functions for pattern-matching reduction, useful for accumulating state over input streams, like tracking user behavior in e-commerce flows.
Works in both Clojure and ClojureScript, with macros for precompilation in Clojure to improve startup times in ClojureScript applications.
Provides `automat.viz/view` to visualize automata states and transitions in Clojure, aiding in debugging and understanding complex FSMs.
Cons
Using the `$` operator for reduction can impact performance, as the README notes it's better to use `:start-index` and `:stream-index` for bulk processing in high-throughput cases.
Visualization via `automat.viz/view` is only available in Clojure, not in ClojureScript, reducing debugging capabilities in browser environments.
Requires familiarity with functional programming and state machine concepts, making it less accessible for developers new to these paradigms or Clojure's macro system.
Tied to the Clojure ecosystem, so it doesn't integrate with non-Clojure tools or libraries, which can be a constraint in polyglot projects.
Frequently Asked Questions
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