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Flow Language Wiki

Flow is a statically-typed, interpreted programming language designed for music production. It combines general-purpose programming with music-specific syntax and semantics, providing a seamless path from composition to audio export. The interpreter is written in C# targeting .NET 9.

Key Features

• Static typing with music-aware types (Note, Chord, Sequence, Song, Bar, Voice, Track, Buffer, etc.)
• Flow operator (->) for elegant function chaining and effect pipelines
• Inline note streams (| C4 D4 E4 F4 |) with durations, dynamics, articulation, ornaments
• Musical context blocks — tempo, timesig, key, swing, dynamics, pan, gain, rit, accel
• Pattern transforms — transpose, invert, retrograde, augment, diminish, humanize, trill, tremolo, vary, and more
• Chord progressions with voice leading (progression | I IV V I |)
• Built-in synthesizers — piano, brass, sax, flute, organ, bell, strings, drums, sine, and custom wavetables
• Audio effects — reverb, filters, compressor, sidechain, delay, gain, panning, fades
• Song structure — sections, arrangements with repeats, multi-track voices
• Harmony — chord literals, roman numerals, scales, arpeggios
• Generative features — Euclidean rhythms, weighted / seeded random choice, diatonic variation, polyrhythms
• Vocalization — formant-synthesized vowels/syllables and a TTS hook
• Loops, string interpolation, lambdas, closures, higher-order functions
• Playback — blocking play, non-blocking stream, loop, preview
• Export — WAV (16/24/32-bit) and Standard MIDI Files

Wiki Pages

Getting Started

• Quick Start — Install, build, and run your first script

Core Language

• Language Basics — Variables, types, operators, comments, scoping
• Functions — Procedures, lambdas, closures, overloading
• Flow Operator — The -> pipe operator
• Collections — Arrays and list operations
• Loops — for, while, break, continue
• String Interpolation — $"..." syntax

Music Features

• Note Streams — Inline musical notation
• Musical Context — Tempo, key, time signature, swing, dynamics, pan, gain, rit/accel
• Chords and Harmony — Chord literals, roman numerals, scales
• Chord Progressions — Voice-led progression | I IV V I |
• Song Structure — Sections, songs, arrangements

Expression and Transforms

• Pattern Transforms — Transpose, invert, retrograde, humanize, trill, tremolo, vary, polyrhythm, tempoRamp
• Dynamics and Expression — Dynamics, articulation, ornaments
• Generative Music — Euclidean rhythms, random choice, vary, polyrhythms

Audio

• Audio and Synthesis — Buffers, oscillators, envelopes, synthesizers, custom wavetables
• Effects — Reverb, filters, compressor, sidechain, delay, gain, panning
• Voices and Tracks — Multi-track timeline rendering
• Vocalization — Formant-synthesized singing and TTS
• Visualization — ASCII piano-roll and waveform
• Playback and Export — play, stream, WAV export, MIDI export, loading WAVs

Reference

• Standard Library — Modules and complete function reference
• Imports and Modules — The use statement and module system
• Tips and Tricks — Idioms, shorthands, and common pitfalls
• Examples — Complete working programs

Quick Example

use "@std"
use "@audio"

tempo 120 {
    timesig 4/4 {
        key Cmajor {
            section intro {
                Sequence melody = | C4q E4q G4q C5q | -> crescendo 0.2 0.7
            }
            section hook {
                Sequence chords = progression | I IV V I |
            }

            Song mySong = [intro hook*2]
            Buffer rendered = (renderSong mySong "piano")
            Buffer final = rendered -> reverb 0.3 -> fadeOut 0.5

            (exportWav final "my_song.wav")
            (writeMidi "my_song.mid" mySong)
            (print $"rendered {(getFrames final)} frames")
        }
    }
}