Banish: A declarative framework for rule-based state machines in Rust

Name: Banish: A declarative framework for rule-based state machines in Rust
Availability: InStock
Author: LoganFlaherty

by LoganFlaherty·Mar 22, 2026·1 point·0 comments

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AI Analysis

●●SolidWizardryNiche Gem

Compile-time generated scheduler beats manual match-loop-state hell for complex state machines.

Strengths

•Proc macro generates the runtime scheduler at compile time instead of interpreting at runtime.
•Async-runtime-agnostic design works with tokio, async-std, or smol without integration code.
•Runtime dispatch via BanishDispatch trait enables resumable, externally-configurable machines.

Weaknesses

•State machine libraries already exist in Rust (smlang, state_machine_future).
•Niche audience limits adoption to developers with genuinely complex state requirements.

Post Description

Banish generates a fixed-point runtime at compile time and schedules your states through it. You declare states and rules, the framework decides when they run. Release 1.3.0 adds async support, runtime dispatch, block attributes, transition guards, and scoped variable declarations, rounding out what I think is a genuine framework-level feature set for a category of problem that usually ends up as a loop wrapping a match wrapping a pile of flags.

The before/after comparison in the README shows the difference pretty concisely. Happy to answer questions about the design tradeoffs, particularly around the proc macro implementation. Thanks for reading.