This is an Elm 0.18 pseudo-library for Web-MIDI. It started life as an almost direct translation from elm-webmidi (elm 0.16) which was deprecated a year or so ago because it made heavy use of signals which suddenly vanished from the language. The analogue of signals in Elm 0.18 is subscriptions which act through ports. However, one downside of ports is that their use precludes publication in the Elm package repository.
This version has one advantage over its predecessor - MIDI Event messages are now properly parsed using the elm-comidi parser which means that the full range of such messages is now supported.
The only processing that is done on the message stream is to recognise volume control messages and thus to save to state the current maximum volume. This allows programs that use the module to respond to the volume control as notes are played.
You will need to attach a MIDI device to your computer to see any effect from Web-MIDI. At the time of writing, Chrome has the best support. Recent versions of Opera and Firefox support it but playback seems unresponsive. Other browsers will fail to initialise or fail to respond (say) to key presses on a MIDI keyboard.
To build, run make and browse to webmidi.html
This project has been tested using an M-Audio KeystationMini32 keyboard.
cd to the examples directory to see the sample programs.
(Examples have a dependency on elm-soundfont-ports which uses native code and which consequently is debarred from publication on http://package.elm-lang.org/. As a workaround, the elm code is reproduced in the SoundFont of the examples.)
Basic.elm is functionally identical to WebMidi.elm. It simply illustrates how you might embed the WebMidi module inside a larger program (but in this case this program does nothing else).
Piano.elm allows you to plug in your MIDI keyboard or other MIDI device and play it as a piano. It works simply by loading the piano soundfont which is served as a local resource, initialising web-midi and requesting that any NoteOn events should be played through the soundfont.
Send.elm allows you to send MIDI note on and off messages to any connected MIDI device.
MidiInstrument.elm allows you to plug in your MIDI keyboard or other MIDI device and to choose the instrumental sound it makes. In this case, the soundfonts are loaded directly from Benjamin Gleitzman's github package of pre-rendered sound fonts. These may take a little longer to load.
To build, invoke compilemi.sh and browse to midiInstrument.html.
This would be the basis of an ideal component for anyone wishing to write a web-audio synthesiser in elm which might respond to a larger selection of control messages.
elm-lang/core 5.1.1
elm-lang/html 2.0.0
newlandsvalley/elm-comidi 3.0.0
Travis CI enforces that all code is formatted with elm-format.
To do this:
npm install -g elm-formatmake format