Pipes & Holes

The pipe operator (|>) and hole (%) are the foundation of Akkado's signal flow model.

The pipe operator (|>) and hole (%) are the foundation of Akkado’s signal flow model.

The Pipe Operator |>

The pipe operator connects audio processing nodes, creating a signal flow graph.

// Signal flows left to right
osc("saw", 220) |> lp(%, 800) |> out(%, %)

This reads as: “Generate a sawtooth at 220 Hz, pipe it through a lowpass filter at 800 Hz, then pipe to the output.”

Why Pipes?

Pipes make signal flow explicit and readable:

// Without pipes (harder to read)
out(lp(osc("saw", 220), 800), lp(osc("saw", 220), 800))

// With pipes (clearer)
osc("saw", 220) |> lp(%, 800) |> out(%, %)

The Hole %

The hole (%) is a placeholder that gets filled with the signal from the left side of the pipe.

Single Hole

When you use % once, it receives the piped signal:

osc("sin", 440) |> out(%, %)
//           ^    ^
//           |    |
//           Both holes filled with osc("sin", 440)

Multiple Holes

You can use % multiple times in the same expression:

// Send signal to both filter and output
osc("sin", 440) |> lp(%, 1000) + % |> out(%, %)
//                          ^
//                          Original unfiltered signal mixed back in

Hole with Math

The hole can be used in calculations:

// Reduce volume by half
osc("sin", 440) |> % * 0.5 |> out(%, %)

// Add DC offset
osc("sin", 440) |> % + 0.5 |> out(%, %)

Chaining Pipes

Build complex signal chains by connecting multiple pipes:

// Oscillator -> Filter -> Distortion -> Output
osc("saw", 110) |> lp(%, 800) |> saturate(%, 2) |> out(%, %)

Branching

The hole lets you create parallel paths:

// Dry/wet mix
osc("saw", 110) |> lp(%, 500) * 0.7 + % * 0.3 |> out(%, %)
//          filtered (wet)    original (dry)

Examples

Basic Synth Voice

// Oscillator through filter with envelope
osc("saw", 220) * adsr(trigger(2), 0.01, 0.2) |> lp(%, 1000) |> out(%, %)

Effects Chain

// Guitar-like processing
osc("saw", 110) |> saturate(%, 3) |> lp(%, 2000) |> delay(%, 0.3, 0.4) |> out(%, %)

Stereo Processing

// Stereo spread
osc("saw", 220) |> out(lp(%, 500), lp(%, 2000))