alda.lisp

Under the hood, Alda transforms input (i.e. Alda code) into Clojure code which, when evaluated, produces a map of score information, which the audio component of Alda can then use to make sound. This Clojure code is written in a DSL called alda.lisp. See below for an example of alda.lisp code and the result of evaluating it.

Parsing demo

You can use the parse task to parse Alda code into alda.lisp (-l/--lisp) and/or evaluate it to produce a map (-m/--map) of score information.

$ alda parse --lisp -f examples/hello_world.alda

(alda.lisp/score
 (alda.lisp/part
  {:names ["piano"]}
  (alda.lisp/note
   (alda.lisp/pitch :c)
   (alda.lisp/duration (alda.lisp/note-length 8)))
  (alda.lisp/note (alda.lisp/pitch :d))
  (alda.lisp/note (alda.lisp/pitch :e))
  (alda.lisp/note (alda.lisp/pitch :f))
  (alda.lisp/note (alda.lisp/pitch :g))
  (alda.lisp/note (alda.lisp/pitch :f))
  (alda.lisp/note (alda.lisp/pitch :e))
  (alda.lisp/note (alda.lisp/pitch :d))
  (alda.lisp/note
   (alda.lisp/pitch :c)
   (alda.lisp/duration (alda.lisp/note-length 2 {:dots 1})))))

$ alda parse --map -f examples/hello_world.alda

{:chord-mode false,
 :current-instruments #{"piano-Id8yG"},
 :events
 #{{:offset 250.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 62,
    :pitch 293.6647679174076,
    :duration 225.0,
    :voice nil}
   {:offset 2000.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 60,
    :pitch 261.6255653005986,
    :duration 1350.0,
    :voice nil}
   {:offset 0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 60,
    :pitch 261.6255653005986,
    :duration 225.0,
    :voice nil}
   {:offset 500.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 64,
    :pitch 329.6275569128699,
    :duration 225.0,
    :voice nil}
   {:offset 750.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 65,
    :pitch 349.2282314330039,
    :duration 225.0,
    :voice nil}
   {:offset 1000.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 67,
    :pitch 391.99543598174927,
    :duration 225.0,
    :voice nil}
   {:offset 1250.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 65,
    :pitch 349.2282314330039,
    :duration 225.0,
    :voice nil}
   {:offset 1500.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 64,
    :pitch 329.6275569128699,
    :duration 225.0,
    :voice nil}
   {:offset 1750.0,
    :instrument "piano-Id8yG",
    :volume 1.0,
    :track-volume 0.7874015748031497,
    :panning 0.5,
    :midi-note 62,
    :pitch 293.6647679174076,
    :duration 225.0,
    :voice nil}},
 :beats-tally nil,
 :instruments
 {"piano-Id8yG"
  {:octave 4,
   :current-offset {:offset 3500.0},
   :key-signature {},
   :config {:type :midi, :patch 1},
   :duration 3.0,
   :min-duration nil,
   :volume 1.0,
   :last-offset {:offset 2000.0},
   :id "piano-Id8yG",
   :quantization 0.9,
   :duration-inside-cram nil,
   :tempo 120,
   :panning 0.5,
   :current-marker :start,
   :time-scaling 1,
   :stock "midi-acoustic-grand-piano",
   :track-volume 0.7874015748031497}},
 :markers {:start 0},
 :cram-level 0,
 :global-attributes {},
 :nicknames {},

$ alda parse --lisp -c 'cello: c+'

(alda.lisp/score
  (alda.lisp/part {:names ["cello"]}
    (alda.lisp/note (alda.lisp/pitch :c :sharp))))