Euterpea is a domain specific language in Haskell for writing music.
The following program will play the C4 note for 1 beat (1 quarter note qn or 0.25), and then it'll play the E3 and E4 notes simultaneously for 2 beats (0.5 or a half note hn).
play (c 4 qn :+: e 3 0.5)
- Install a Haskell compiler
- Install Euterpea
- Install VMPK (Virtual MIDI Piano Keyboard) or another MIDI server
- Run VMPK or your other MIDI server
- You should see a Keyboard appear
- You may need to enable the feature so that it opens a MIDI input device
- Run app/Main.markdown
- This file is a literate Haskell file, you're reading it right now.
- By default, it'll connect to MIDI output device
2.
If it doesn't work, try using another MIDI output device, such as device 1.
If you're using Haskell stack, simply type:
stack run
import EuterpeaThis song is played at 64 beats per minute.
Dur is Euterpea's type for specifying a rational-valued time duration.
bpm :: Dur
bpm = 64The song is in A major.
I think the "base" key is A3, which would be an octave below A4 (440Hz?).
I'm not sure how to change Euterpea to A major, so this Music jumps around an octave and doesn't sound right.
-- Ignore that this is an unused top-level binding by prefixing the name with an underscore
-- -Wunused-top-binds
_gaga_you_and_i__a_major :: Music Pitch
_gaga_you_and_i__a_major = configure
$ cs base t
:+: b base t
:+: cs base t2
:+: cs base t2
:+: cs base t
:+: b base t
:+: cs base t3
:+: rest hn
:+: d base t
:+: cs base t
:+: d base t2
:+: d base t2
:+: d base t
:+: cs base t
:+: d base t
:+: cs base t2
:+: e base t3
:+: rest hn
:+: a (1 + base) t2
:+: fs base t2
:+: e base t2
:+: fs base t2
:+: a (1 + base) t
:+: fs base t2
:+: e base t2
:+: a base t2
:+: cs base t3
where t = qn
t2 = hn
t3 = dhn
base = 3I rewrote the song in C major, and Euterpea plays it correctly.
gaga_you_and_i :: Music Pitch
gaga_you_and_i = configure
-- It's been a long time since you've came around
$ c base t
:+: d base t
:+: e base t2
:+: e base t2
:+: e base t
:+: d base t
:+: e base t2
:+: e base t
:+: e base t3
:+: rest hn
:+: c base t
:+: e base t
:+: f base t2
:+: f base t2
:+: f base t
:+: e base t
:+: f base t
:+: e base t2
:+: g base t3
:+: rest hn
:+: c (1 + base) t2
:+: a base t2
:+: g base t2
:+: a base t2
:+: c (1 + base) t
:+: a base t2
:+: g base t2
:+: c base t2
:+: e base t3
where t = qn
t2 = hn
t3 = dhn
base = 4This function will set the MIDI musical instrument and the tempo.
configure :: Music a -> Music a
configure = instrument AcousticGrandPiano . tempo desiredTempoThe MIDI tempo is the amount of microseconds per quarter note. This song is in BPM (e.g. 64 beats per minute). A quarter note is 1 beat. So there are 64 beats (quarter notes) in 60 seconds. There are 64 / 60 microseconds per beat.
Unfortunately, this doesn't sound right so I double the tempo (2 * bpm)...
where desiredTempo = 2 * bpm / 60Change the MIDI device if this causes you trouble...
midiDevice :: Int
midiDevice = 2The entrypoint will print the song's duration and play the song.
main :: IO ()
main = do
print duration
print $ (fromRational duration :: Double)
playDev midiDevice $ song
where
duration = dur song
song = gaga_you_and_iInstall the haskell-vim plugin for good syntax highlighting and other features.
You might need this:
set ft=markdown
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