Euterpea

How to start

Start fluidsynth with your startfluidsynth script. Start qjackctl, and connect midi through to fluidsynth. Test fluidsynth with noteon 1 60 120. Now open ghci and import Euterpea. Try play $ note qn (pitch 64).

Using GHCI

Start ghci from the root directory with ghci -isrc to give ghci access to all modules in the src directory.

Useful Euterpea Functions

:info InstrumentName - List available MIDI instruments :info PercussionSound - List available percusssion sounds

File Heirarchy

Chords and scales are just descriptions of numerical patterns and shouldn't need to import other files or Euterpea. Utils can make use of that info and also import Euterpea.

Composition Types

Patterns are organized in layers to make it simple to move from primitive numerical patters to complete compositions as follows:

Patterns: Simple numerical patterns describing numerical relationships in a pre-musical form
Sequences: Patterns applied to a scale, but without rhythm
Melodies: Sequences with rhythm
Clips: Melodies that specify an instrument
Scenes: Arrangements of clips
Compositions: Arrangements of scenes

This workflow resembles working with something like Ableton Live, but has a shortcoming in that it encouraged block and loop-based composition and discourages melodic independence and unclearly separated musical sections.

Types in Euterpea

Pitch vs absPitch

An AbsPitch is a midi note, like 64.

type AbsPitch = Int

A Pitch is the form you will usually consume, and has the type:

type Pitch = (PitchClass, Octave)

The pitch, and absPitch functions convert midi note (Int) pitches to Pitch and vice versa.

Types

A composition that you can play using the play function is of the type Music a, which is a recursive data type defined as:

data Music a
  = Prim (Primitive a)
  | (Music a) :+: (Music a)
  | (Music a) :=: (Music a)
  | Modify Control (Music a)

So to get a Music a, you just need to make a Primitive a:

data Primitive a = Note Dur a | Rest Dur

and wrap it with Prim.

Examples:

Prim (Note (1/32) (Gs,4))

Prim (note qn (C,4))

These examples are both of type Music Pitch

You can concatenate Music a values with :+: or layer them with :=: and still have a Music a, since Music a is a recursive data type.

Often you'll end up with something of type [Music Pitch], which is just a bunch of notes that you need to concatenate into a Music Pitch. This is what the line function is good for.

line :: [Music a] -> Music a

It's equivalent to foldr (:+:) (rest 0).

Note that Music a is an instance of ToMusic1 a, which is required for it to be played as MIDI or written to a MIDI file.

cowgirl-coding/euterpea-sketches