Getting started

Hibiki has no runtime dependencies and requires Ruby >= 3.4.

Installation

# Gemfile
gem "hibiki"

Or install it directly:

gem install hibiki

Two flavors

The DSL gives you bare state / derived / effect helpers. It is strictly opt-in:

require "hibiki"
include Hibiki::DSL

x = state(0)
y = derived { x.value + 1 }

x.value = 10
y.value # => 11

Prefer no DSL? We get you. Use the classes directly:

require "hibiki"

x = Hibiki::State.new(0)
y = Hibiki::Derived.new { x.value + 1 }

x.value = 10
y.value # => 11

The three primitives

state(v) — a writable signal. Reading .value registers a dependency; writing notifies subscribers. Writing an ==-equal value is a no-op.

counter = state(0)
counter.value += 1
counter.update { it + 1 } # Ruby's in-place sugar

derived { } — a lazy computed signal. It recomputes on read when marked dirty (when any state it depends on changes), never on write, and caches its value until a dependency changes.

doubled = derived { counter.value * 2 }
doubled.value # => 4

effect { } — an eager side effect. It runs immediately and re-runs whenever a dependency (any state inside the effect block) changes.

name = state("world")
effect { puts "hello, #{name.value}!" } # prints "hello, world!"

name.value = "Ruby"                     # prints "hello, Ruby!"