A Hydra patch is a left-to-right chain of dot-joined functions, modeled on modular-synth cabling

Hydra’s core metaphor is the modular synthesizer: instead of connecting modules with patch cables, you chain JavaScript functions with dot notation, and numeric arguments play the role of knob positions. A valid patch is a pipeline: it starts with a source function that generates a signal, applies transformation functions that change geometry or color, and terminates with .out() to route the result to an output buffer. Data flows left to right — each function receives the previous step’s texture as implicit input — so osc().rotate().out() reads as oscillator into rotation module into output. Functions can be added, removed, or reordered along the chain like re-patching, which is what gives Hydra its composability. This makes signal-flow intuition transfer both ways: someone with modular-synth experience can build patches immediately, and Hydra teaches signal-flow thinking to people who have never touched a Eurorack. The chaining model is the prerequisite for all other Hydra concepts.

Examples

osc(60, 0.1, 0.5).rotate(0.5).pixelate(20).out()

Source (osc) -> geometry transform (rotate) -> geometry transform (pixelate) -> output; compare to VCO -> VCF -> output in Eurorack.

Assessment

Map a three-module Eurorack patch (VCO -> VCF -> VCA) onto a Hydra chain, then add a fourth function and say what it does to the signal. Given a broken chain (missing .out(), or a transform before any source), identify and fix the error, then write a minimal three-step chain from scratch.