Anamorphism

Main.purs

module Main where

import Prelude

import Data.NonEmpty ((:|))
import Effect (Effect)
import Data.Function (on)
import WAGS.Lib.Learn (play)
import WAGS.Lib.Learn.Note (accelerando, noteFromPitch_, repeat, seq)
import WAGS.Lib.Learn.Pitch (at, fuse, c4, d4, e4, fSharp4, gSharp4, bFlat4, c5, wholeTone)
import WAGS.Lib.Cofree (ana)

main :: Effect Unit
main =
  play
    $ map fuse
    $ (map <<< map) _.note
    $ ana
        ((<*>) \time { note, rising } ->
            if on (>=) (at time) note c5 then { note: bFlat4, rising: false }
            else if on (<=) (at time) note c4 then { note: d4, rising: true }
            else { note: (if rising then add else sub) note wholeTone, rising }
        )
        (const { note: c4, rising: true })