From 2ffb6d05f4519d2185425e45a5d85f32282ca031 Mon Sep 17 00:00:00 2001
From: Ludvig Gunne Lindström <ludviggunnelindstrom@gmail.com>
Date: Sun, 8 Nov 2026 13:30:11 +0100
Subject: add synth example

---
 synth/main.lua | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 synth/main.lua

diff --git a/synth/main.lua b/synth/main.lua
new file mode 100644
index 0000000..42fd82b
--- /dev/null
+++ b/synth/main.lua
@@ -0,0 +1,119 @@
+local ml = require 'melisma.lazy'
+
+ml.util.openmodule(ml.functional)
+
+local argv = ml.internal.argv
+local device = argv[1]
+
+if not device then
+  print('Usage: melisma -C synth main.lua DEVICE')
+  print('Available devices are:')
+
+  for _,source in ipairs(ml.port.midi.sources()) do
+    print('\t'..source)
+  end
+
+  os.exit(1)
+end
+
+local mport = ml.port.midi.input.open('midi-in')
+
+print(string.format('Connecting device \'%s\'', device))
+mport:connect(device)
+
+local wt = ml.oscil.wavetable.saw()
+wt = wt + wt:scale(2)
+
+local size = 8
+local active = replicate(false, size)
+local allocs = replicate(nil, 128)
+local oscil = replicate(bind(ml.oscil.init, wt, 0, 0), size)
+local interp = replicate(bind(ml.interp.init, 0), size)
+
+zip(ml.oscil.mapa, oscil, interp)
+
+local mix = ml.mixer.init(table.unpack(oscil))
+local delay = ml.delay.init(mix)
+  :delay(0.2)
+  :feedback(0.4)
+  :wetdrymix(0.5)
+  :gain(0.8)
+local lowpass = ml.biquad.lowpass.init(delay)
+  :cutoff(4000)
+  :resonance(0.7)
+local aport = ml.port.audio.output.open('audio-out', lowpass)
+local dests = ml.port.audio.destinations()
+
+fmap(bind(aport.connect, aport), dests)
+
+local attack = 0.025
+local release = 0.05
+
+local function handle_on(key, vel)
+  print('on', key)
+
+  -- Check if this note is already on
+  if allocs[key] then return end
+
+  -- Find unused oscillator
+  local i = nil
+  for j = 1,size do
+    if not active[j] then
+      i = j
+      break
+    end
+  end
+  if not i then return end
+
+  -- Play the note
+  print('activate oscillator', i)
+  active[i] = true
+  allocs[key] = i
+  interp[i]:linear(vel / 127.0, attack)
+
+  local f = 440 * 2^((key - 57) / 12.0)
+  print('frequency', f)
+  oscil[i]:setf(f)
+end
+
+local function free(args)
+  -- Mark the oscillator as unused after the note is released
+  local i, key = table.unpack(args)
+  print('free oscillator', i)
+  active[i] = false
+  allocs[key] = nil
+end
+
+local function handle_off(key)
+  print('off', key)
+
+  -- Find the oscillator
+  local i = allocs[key]
+  if not i then return end
+
+  -- Stop playing the note
+  print('deactivate oscillator', i)
+  interp[i]:linear(0, release)
+  ml.event.schedule(release, free, { i, key })
+end
+
+mport:callback(function(msg)
+  local status = msg.status & 0xf0
+  local key = msg.data1
+  local vel = msg.data2
+
+  print('received', status, key, vel)
+
+  local off = 0x80
+  local on = 0x90
+
+  if status == off then
+    handle_off(key)
+    return
+  end
+
+  if status == on then
+    handle_on(key, vel)
+    return
+  end
+end)
-- 
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