major refactoring: Const, Stream + ResultNode

13 files changed, 270 insertions, 182 deletions

diff --git a/lib/debug.moon b/lib/debug.moon
index ece365f..f642c2e 100644
--- a/lib/debug.moon
+++ b/lib/debug.moon
@@ -3,12 +3,10 @@ import Op from require 'core'
 class out extends Op
   @doc: "(out name-str value) - log value to the console"
 
-  setup: (name, @chld) =>
-    @name = name\getc!
+  setup: (@name, @value) =>
 
   update: (dt) =>
-    @chld\update dt
-    L\print "@name", @chld\get!
+    L\print "#{@name\unwrap 'str'}", @value\unwrap!
 
 {
   :out
diff --git a/lib/envelope.moon b/lib/envelope.moon
index 8e8fafe..eb79a64 100644
--- a/lib/envelope.moon
+++ b/lib/envelope.moon
@@ -1,4 +1,4 @@
-import Const, Op, Scope, eval from require 'core'
+import Stream, Op, Scope, eval from require 'core'
 
 class ar_core extends Op
   @doc: "(ar-core attack release gate)
@@ -8,21 +8,18 @@ goes from 0 to 1 in attack seconds, holds while gate is on, then goes back to 0
 
   new: (...) =>
     super ...
-    @value = 0
+    @out = Stream 'num', 0
 
   setup: (@a, @r, @gate) =>
     assert @a, "ar requires an attack value"
     assert @r, "ar requires a release value"
     assert @gate, "ar requires a gate value"
+    @out
 
   update: (dt) =>
-    @a\update dt
-    @r\update dt
-    @gate\update dt
+    slope = if (@gate\unwrap 'bool') then (@a\unwrap! or 0.1) else -(@r\unwrap! or 0.5)
 
-    slope = if @gate\get! then (@a\get! or 0.1) else -(@r\get! or 0.5)
-
-    @value = math.min 1, math.max 0, @value + dt / slope
+    @out\set math.min 1, math.max 0, @out\unwrap! + dt / slope
 
 scope = Scope.from_table { 'ar-core': ar_core }
 scope\set 'ar', eval '(fn (a r) (fn (gate) (ar-core a r gate)))', scope
diff --git a/lib/gui.moon b/lib/gui.moon
index a2fee4b..474de5c 100644
--- a/lib/gui.moon
+++ b/lib/gui.moon
@@ -12,12 +12,11 @@ display value as a bar"
 
   setup: (name, @chld) =>
     @@instances[@name] = nil if @name
-    @name = name\getc!
+    @name = name\const!\unwrap!
     @@instances[@name] = @
 
   update: (dt) =>
-    @chld\update dt
-    @value = @chld\get!
+    @value = @chld\unwrap!
 
   destroy: =>
     @@instances[@name] = nil
@@ -44,9 +43,11 @@ class key extends Op
 
   setup: (@key) =>
     assert @key
+    @out = Stream 'bool', false
+    @out
 
   update: (dt) =>
-    @value = lk.isDown @key\get!
+    @out\set lk.isDown @key\unwrap!
 
 arguments, k = {}
 for a in *arg
diff --git a/lib/logic.moon b/lib/logic.moon
index 1c274dd..c476033 100644
--- a/lib/logic.moon
+++ b/lib/logic.moon
@@ -1,37 +1,36 @@
-import Op from require 'core'
+import Stream, Op from require 'core'
 unpack or= table.unpack
 
 class BinOp extends Op
+  new: (...) =>
+    super ...
+    @out = Stream 'bool'
+
   setup: (...) =>
     @children = { ... }
     assert #@children >= 2, "#{@} needs at least two parameters"
-
-  update: (dt) =>
-    for child in *@children
-      child\update dt
+    @out
 
 class eq extends BinOp
   @doc: "(eq a b [c]...)
 (== a b [c]...) - check for equality"
 
   update: (dt) =>
-    super\update dt
-
-    @value = true
-    val = @children[1]\get!
+    equal = true
+    val = @children[1]\unwrap!
     for child in *@children[2,]
-      @value and= val == child\get!
+      equal and= val == child\unwrap!
+    @out\set equal
 
 
 class and_ extends BinOp
   @doc: "(and a b [c]...) - AND values"
 
   update: (dt) =>
-    super\update dt
-
-    @value = true
+    value = true
     for child in *@children
-      @value and= child\get!
+      value and= child\unwrap!
+    @out\set value
 
 class or_ extends BinOp
   @doc: "(or a b [c]...) - OR values
@@ -39,31 +38,30 @@ class or_ extends BinOp
 subtracts all other arguments from a"
 
   update: (dt) =>
-    super\update dt
-
-    @value = false
+    value = false
     for child in *@children
-      @value or= child\get!
+      value or= child\unwrap!
+    @out\set value
 
 class not_ extends Op
   @doc: "(not a) - boolean opposite"
 
   setup: (@a) =>
+    @out = Stream 'bool'
+    @out
 
   update: (dt) =>
-    @a\update dt
-
-    @value = not @a\get!
+    @out\set not @a\unwrap!
 
 class bool extends Op
   @doc: "(bool a) - convert to bool"
 
   setup: (@a) =>
+    @out = Stream 'bool'
+    @out
 
   update: (dt) =>
-    @a\update dt
-
-    @value = switch @a\get!
+    @out\set switch @a\unwrap!
       when false, nil, 0
         false
       else
diff --git a/lib/math.moon b/lib/math.moon
index 54d3440..68dae3a 100644
--- a/lib/math.moon
+++ b/lib/math.moon
@@ -1,25 +1,25 @@
-import Op from require 'core'
+import Stream, Op, Const from require 'core'
 unpack or= table.unpack
 
 class BinOp extends Op
+  new: (...) =>
+    super ...
+    @out = Stream 'num', 0
+
   setup: (...) =>
     @children = { ... }
     assert #@children >= 2, "#{@} needs at least two parameters"
-
-  update: (dt) =>
-    for child in *@children
-      child\update dt
+    @out
 
 class add extends BinOp
   @doc: "(+ a b [c]...)
 (add a b [c]...) - add values"
 
   update: (dt) =>
-    super\update dt
-
-    @value = 0
+    value = 0
     for child in *@children
-      @value += child\get!
+      value += child\unwrap 'num'
+    @out\set value
 
 class sub extends BinOp
   @doc: "(- a b [c]...)
@@ -28,22 +28,20 @@ class sub extends BinOp
 subtracts all other arguments from a"
 
   update: (dt) =>
-    super\update dt
-
-    @value = @children[1]\get!
+    value = @children[1]\unwrap 'num'
     for child in *@children[2,]
-      @value -= child\get!
+      value -= child\unwrap 'num'
+    @out\set value
 
 class mul extends BinOp
   @doc: "(* a b [c]...)
 (mul a b [c]...) - multiply values"
 
   update: (dt) =>
-    super\update dt
-
-    @value = 1
+    value = 1
     for child in *@children
-      @value *= child\get!
+      value *= child\unwrap 'num'
+    @out\set value
 
 class div extends BinOp
   @doc: "(/ a b [c]...)
@@ -52,11 +50,26 @@ class div extends BinOp
 divides a by all other arguments"
 
   update: (dt) =>
-    super\update dt
-
-    @value = @children[1]\get!
+    value = @children[1]\unwrap 'num'
     for child in *@children[2,]
-      @value /= child\get!
+      value /= child\unwrap 'num'
+    @out\set value
+
+evenodd_op = (name, remainder) ->
+  class k extends Op
+    setup: (@a, @div=Const.num 2) =>
+      @out = Stream 'bool'
+      @out
+
+    update: (dt) =>
+      a, divi = (@a\unwrap 'num'), @div\unwrap 'num'
+      @out\set (a % divi) == remainder
+
+  k.__name = name
+  k.doc = "(#{name} a [div]) - check for #{name} divison
+
+div defaults to 2"
+  k
 
 func_op = (name, arity, func) ->
   k = class extends Op
@@ -65,12 +78,11 @@ func_op = (name, arity, func) ->
       if arity != '*'
         assert #@params == arity, "#{@} needs exactly #{arity} parameters"
 
-    update: (dt) =>
-      params = for param in *@params
-        param\update dt
-        param\get!
+      @out = Stream 'num'
+      @out
 
-      @value = func unpack params
+    update: (dt) =>
+      @out\set func unpack [p\unwrap 'num' for p in *@params]
 
   k.__name = name
   k
@@ -85,6 +97,8 @@ module = {
   :mod, '%': mod
 
   mix: func_op 'mix', 3, (a, b, i) -> i*b + (1-i)*a
+  even: evenodd_op 'even', 0
+  odd: evenodd_op 'odd', 1
 
   pi: math.pi, huge: math.huge
 }
diff --git a/lib/midi/core.moon b/lib/midi/core.moon
index ea49a2c..891de0a 100644
--- a/lib/midi/core.moon
+++ b/lib/midi/core.moon
@@ -51,8 +51,10 @@ class Input
 
   -- register a handler
   -- mask is { :status, :chan, :a } (all keys optional)
+  -- returns mask for op convenience
   attach: (mask, handler) =>
     @listeners[mask] = handler
+    mask
 
   detach: (mask) =>
     @listeners[mask] = nil
@@ -83,8 +85,23 @@ class InOut
   detach: (...) => @inp\detach ...
   send: (...) => @out\send ...
 
+apply_range = (range, val) ->
+  if range.type == 'str'
+    switch range\unwrap!
+      when 'raw' then val
+      when 'uni' then val / 128
+      when 'bip' then val / 64 - 1
+      when 'rad' then val / 64 * math.pi
+      else
+        error "unknown range #{@range}"
+  elseif range.type == 'num'
+    val / 128 * range\unwrap!
+  else
+    error "range has to be a string or number"
+
 {
   :Input
   :Output
   :InOut
+  :apply_range
 }
diff --git a/lib/midi/init.moon b/lib/midi/init.moon
index f522b6c..c9e2476 100644
--- a/lib/midi/init.moon
+++ b/lib/midi/init.moon
@@ -1,29 +1,29 @@
-import Const, Op from require 'core'
-import Input from require 'lib.midi.core'
+import Stream, Const, Op from require 'core'
+import Input, apply_range from require 'lib.midi.core'
 
-dispatch = Input 'system:midi_capture_6'
+dispatch = Input 'system:midi_capture_4'
 
 class gate extends Op
   @doc: "(midi/gate note [chan]) - gate from note-on and note-off messages"
 
-  new: (...) =>
-    super ...
-
   destroy: =>
     dispatch\detach @mask if @mask
 
   setup: (note, chan) =>
     dispatch\detach @mask if @mask
 
-    note = note\getc 'num'
-    chan = chan and chan\getc 'num'
+    note = note\const!\unwrap 'num'
+    chan = chan and chan\const!\unwrap 'num'
     @value = false
 
     @mask = dispatch\attach { :chan, a: note }, (status) ->
       if status == 'note-on'
-        @value = true
+        @out\set true
       else if status == 'note-off'
-        @value = false
+        @out\set false
+
+    @out = Stream 'bool', false
+    @out
 
   update: (dt) => dispatch\tick!
 
@@ -43,26 +43,16 @@ range can be one of:
   setup: (cc, chan, @range=Const.str'uni') =>
     dispatch\detach @mask if @mask
 
-    cc = cc\getc 'num'
-    chan = chan and chan\getc 'num'
+    cc = cc\const!\unwrap 'num'
+    chan = chan and chan\const!\unwrap 'num'
 
-    @mask = dispatch\attach { status: 'control-change', :chan, a: cc }, (_, _, _, val) -> @apply val
+    @mask = dispatch\attach { status: 'control-change', :chan, a: cc }, (_, _, _, val) ->
+      @out\set apply_range @range, val
 
-  update: (dt) => dispatch\tick!
+    @out = Stream 'num', 0
+    @out
 
-  apply: (val) =>
-    @value = if @range.type == 'str'
-      switch @range\get!
-        when 'raw' then val
-        when 'uni' then val / 128
-        when 'bip' then val / 64 - 1
-        when 'rad' then val / 64 * math.pi
-        else
-          error "unknown range #{@range}"
-    elseif @range.type == 'num'
-      val / 128 * @range\get!
-    else
-      error "range has to be a string or number"
+  update: (dt) => dispatch\tick!
 
 {
   :gate
diff --git a/lib/midi/launchctl.moon b/lib/midi/launchctl.moon
index c7d7b06..778a724 100644
--- a/lib/midi/launchctl.moon
+++ b/lib/midi/launchctl.moon
@@ -1,66 +1,127 @@
-import Const, Op from require 'core'
-import InOut from require 'lib.midi.core'
+import Stream, Const, Op from require 'core'
+import InOut, apply_range from require 'lib.midi.core'
 import bor, lshift from require 'bit32'
 
-launch = InOut 'system:midi_capture_6', 'system:midi_playback_6'
+launch = InOut 'system:midi_capture_4', 'system:midi_playback_4'
 
 color = (r, g) -> bor 12, r, (lshift g, 4)
 
+class cc_seq extends Op
+  @doc: "(launctl/cc-seq i start chan [steps [range]]) - CC-Sequencer
+
+returns the value for the i-th step steps (buttons starting from start).
+steps defaults to 8.
+
+range can be one of:
+- 'raw' [ 0 - 128[
+- 'uni' [ 0 - 1[ (default)
+- 'bip' [-1 - 1[
+- 'rad' [ 0 - tau[
+- (num) [ 0 - num["
+
+  destroy: =>
+    launch\detach @mask if @mask
+
+  new: =>
+    @steps = {}
+    @out = Stream 'num'
+
+  setup: (@i, start, chan, steps=(Const.num 8), @range=Const.str 'uni') =>
+    launch\detach @mask if @mask
+
+    @start = start\const!\unwrap 'num'
+    @chan = chan\const!\unwrap 'num'
+    steps = steps\const!\unwrap 'num'
+
+    while steps > #@steps
+      table.insert @steps, 0
+    while steps < #@steps
+      table.remove @steps
+
+    @mask = launch\attach { status: 'control-change', chan: @chan }, (_, _, cc, val) -> @change cc, val
+    @out
+
+  change: (cc, val) =>
+    i = cc - @start
+    if i < #@steps
+      @steps[i+1] = val
+
+  update: (dt) =>
+    launch\tick!
+
+    curr_i = (@i\unwrap 'num') % #@steps
+
+    @out\set apply_range @range, @steps[curr_i+1]
+
+
 class gate_seq extends Op
   @doc: "(launctl/gate-seq i start chan [steps]) - Gate-Sequencer
 
-returns true or false for the i-th step steps (buttons starting from start)."
+returns true or false for the i-th step steps (buttons starting from start).
+steps defaults to 8."
 
   destroy: =>
     launch\detach @mask if @mask
 
   new: =>
     @steps = {}
-    @value = false
+    @out = Stream 'bool'
 
   setup: (@i, start, chan, steps=(Const.num 8)) =>
     launch\detach @mask if @mask
 
-    @start = start\getc 'num'
-    @chan = chan\getc 'num'
-    steps = steps\getc 'num'
+    for i=1, #@steps
+      launch\send 'note-on', @chan, (@start+i), 0, color 0, 0
+
+    @start = start\const!\unwrap 'num'
+    @chan = chan\const!\unwrap 'num'
+    steps = steps\const!\unwrap 'num'
 
     while steps > #@steps
       table.insert @steps, false
     while steps < #@steps
       table.remove @steps
 
-    @mask = launch\attach { status: 'note-on', chan: @chan }, (_, _, note, _) -> @toggle note
+    for i=1, steps
+      @display i
+
+    @mask = launch\attach { status: 'note-on', chan: @chan }, (_, _, note, _) ->
+      @toggle note
+
+    @out
 
   toggle: (note) =>
     i = note - @start
     val = @steps[i+1]
     if val != nil
       @steps[i+1] = not val
-      curr_i = (@i\get 'num') % #@steps
-      launch\send 'note-on', @chan, note, light @steps[i+1], i == curr_i
+      curr_i = (@i\unwrap 'num') % #@steps
+      @display i, i == curr_i
+
+  display: (i, active) =>
+    launch\send 'note-on', @chan, (@start + i), light @steps[i+1], active
 
   light = (set, active) ->
     set = if set then 'S' else ' '
     active = if active then 'A' else ' '
     color switch set .. active
       when '  ' then 0, 0
-      when ' A' then 1, 0
-      when 'S ' then 0, 1
-      when 'SA' then 0, 3
+      when ' A' then 1, 1
+      when 'S ' then 1, 0
+      when 'SA' then 3, 1
 
   update: (dt) =>
     launch\tick!
 
-    @i\update dt
-    curr_i = (@i\get 'num') % #@steps
+    curr_i = (@i\unwrap 'num') % #@steps
     prev_i = (curr_i - 1) % #@steps
 
-    launch\send 'note-on', @chan, (@start + curr_i), light @steps[curr_i+1], true
-    launch\send 'note-on', @chan, (@start + prev_i), light @steps[prev_i+1], false
+    @display curr_i, true
+    @display prev_i, false
 
-    @value = @steps[curr_i+1]
+    @out\set @steps[curr_i+1]
 
 {
   'gate-seq': gate_seq
+  'cc-seq': cc_seq
 }
diff --git a/lib/osc.moon b/lib/osc.moon
index dae6737..fed1697 100644
--- a/lib/osc.moon
+++ b/lib/osc.moon
@@ -1,4 +1,4 @@
-import Const, Op, FnDef from require 'core'
+import Stream, Op from require 'core'
 import pack, unpack from require 'osc'
 import dns, udp from require 'socket'
 
@@ -13,12 +13,9 @@ class out extends Op
   setup: (@host, @port, @path, @value) =>
 
   update: (dt) =>
-    for p in *{@host, @port, @path, @value}
-      L\push p\update, dt
-
-    ip = dns.toip @host\get!
-    port = @port\get!
-    msg = pack @path\get!, @value\get!
+    ip = dns.toip @host\unwrap 'str'
+    port = @port\unwrap 'num'
+    msg = pack (@path\unwrap 'str'), @value\unwrap!
     @@udp\sendto msg, ip, port
 
 {
diff --git a/lib/pilot.moon b/lib/pilot.moon
index 1cbc070..2a7d21a 100644
--- a/lib/pilot.moon
+++ b/lib/pilot.moon
@@ -1,5 +1,5 @@
-import Const, Op, FnDef from require 'core'
-import dns, udp from require 'socket'
+import Op from require 'core'
+import udp from require 'socket'
 
 conn = udp!
 hex = "0123456789abcdef"
@@ -18,17 +18,12 @@ send = (tbl) ->
 class play extends Op
   @doc: "(play trig ch oct note [vel [len]]) - play a note when trig is live"
 
-  setup: (@trig, @ch, @oct, @note, @vel, @len) =>
+  setup: (@trig, ...) =>
+    @vals = { ... }
 
   update: (dt) =>
-    vals = for c in *{@trig, @ch, @oct, @note, @vel, @len }
-      c\update dt
-      c\get!
-
-    trig = table.remove vals, 1
-
-    if trig
-      send vals
+    if @trig\unwrap 'bool'
+      send [c\unwrap! for c in *@vals]
 
 class effect extends Op
   @doc: "(effect which a b) - set an effect
@@ -38,10 +33,7 @@ which is one of 'DIS', 'CHO', 'REV' or 'FEE'"
   setup: (@which, @a, @b) =>
 
   update: (dt) =>
-    @which\update dt
-    @a\update dt
-    @b\update dt
-    which, a, b = @which\get!, @a\get!, @b\get!
+    which, a, b = (@which\unwrap 'str'), @a\unwrap!, @b\unwrap!
     if which and a and b
       send { which, a, b }
 {
diff --git a/lib/string.moon b/lib/string.moon
index 82e9702..6a9b7d7 100644
--- a/lib/string.moon
+++ b/lib/string.moon
@@ -1,4 +1,4 @@
-import Op from require 'core'
+import Stream, Op from require 'core'
 
 class str extends Op
   @doc: "(str v1 [v2]...)
@@ -6,12 +6,11 @@ class str extends Op
 
   setup: (...) =>
     @children = { ... }
+    @out = Stream 'str'
+    @out
 
   update: (dt) =>
-    for child in *@children
-      child\update dt
-
-    @value = table.concat [tostring child\get! for child in *@children]
+    @out\set table.concat [tostring child\unwrap! for child in *@children]
 
 {
   :str, '..': str
diff --git a/lib/time.moon b/lib/time.moon
index 89f947e..7ce8b84 100644
--- a/lib/time.moon
+++ b/lib/time.moon
@@ -1,4 +1,4 @@
-import Const, Op from require 'core'
+import Stream, Const, Op from require 'core'
 
 class lfo extends Op
   @doc: "(lfo freq [wave]) - low-frequency oscillator
@@ -12,19 +12,19 @@ wave selects the wave shape from the following (default sin):
   tau = math.pi * 2
   new: (...) =>
     super ...
+    print "creating LFO"
+    @out = Stream 'num'
     @phase = 0
 
   default_wave = Const 'str', 'sin'
   setup: (@freq, @wave=default_wave) =>
     assert @freq, "lfo requires a frequency value"
     L\trace "setup #{@}, freq=#{@freq}, wave=#{@wave}"
+    @out
 
   update: (dt) =>
-    @freq\update dt
-    @wave\update dt
-
-    @phase += dt * @freq\get!
-    @value = switch @wave\get!
+    @phase += dt * @freq\unwrap 'num'
+    @out\set switch @wave\unwrap!
       when 'sin' then .5 + .5 * math.cos @phase * tau
       when 'saw' then @phase % 1
       when 'tri' then math.abs (2*@phase % 2) - 1
@@ -37,45 +37,64 @@ ramps from 0 to max (default same as ramp) once every period seconds"
 
   new: (...) =>
     super ...
+    @out = Stream 'num'
     @phase = 0
+    @out
 
   setup: (@period, @max) =>
     assert @period, "tick requires a period value"
 
   update: (dt) =>
-    @period\update dt
-    max = if @max
-      @max\update dt
-      @max\get!
-    else
-      @period\get!
-
-    @phase += dt / @period\get!
+    period = @period\unwrap 'num'
+    max = if @max then @max\unwrap! else period
+    @phase += dt / period
 
     if @phase >= 1
       @phase -= 1
 
-    @value = @phase * max
+    @out\set @phase * max
 
 class tick extends Op
   @doc: "(tick period) - count ticks
 
-counts upwards every period seconds and returns the number of completed ticks."
+counts upwards by one every period seconds and returns the number of completed ticks."
   new: (...) =>
     super ...
+    @out = Stream 'num'
     @phase = 0
 
   setup: (@period) =>
     assert @period, "tick requires a period value"
+    @out
 
   update: (dt) =>
-    @period\update dt
+    @phase += dt / @period\unwrap 'num'
+    @out\set math.floor @phase
+
+class every extends Op
+  @doc: "(every period) - sometimes true
 
-    @phase += dt / @period\get!
-    @value = math.floor @phase
+returns true once every period seconds."
+  new: (...) =>
+    super ...
+    @out = Stream 'bool'
+    @phase = 0
+
+  setup: (@period) =>
+    assert @period, "every requires a period value"
+    @out
+
+  update: (dt) =>
+    @phase += dt / @period\unwrap 'num'
+    if @phase > 1
+      @phase -= 1
+      @out\set true
+    else
+      @out\set false
 
 {
   :lfo
   :ramp
   :tick
+  :every
 }
diff --git a/lib/util.moon b/lib/util.moon
index af5d8f8..192c489 100644
--- a/lib/util.moon
+++ b/lib/util.moon
@@ -1,4 +1,4 @@
-import Const, Op from require 'core'
+import Stream, Const, Op from require 'core'
 
 class switch_ extends Op
   @doc: "(switch i v0 [v1 v2...]) - switch between multiple inputs
@@ -10,14 +10,16 @@ when i is a num, it is (floor)ed and the matching argument (starting from 0) is
   setup: (@i, ...) =>
     @choices = { ... }
 
-  update: (dt) =>
-    @i\update dt
-    i = @i\get!
+    typ = @choices[1].type
+    for inp in *@choices[2,]
+      assert inp.type == typ, "not all values have the same type: #{typ} != #{inp.type}"
 
-    for choice in *@choices
-      choice\update dt
+    @out = Stream typ
+    @out
 
-    active = switch @i\get!
+  update: (dt) =>
+    i = @i\unwrap!
+    active = switch i
       when true
         @choices[1]
       when false
@@ -25,7 +27,7 @@ when i is a num, it is (floor)ed and the matching argument (starting from 0) is
       else
         i = 1 + (math.floor i) % #@choices
         @choices[i]
-    @value = active and active\get!
+    @out\set active and active\unwrap!
 
 class switch_pause extends Op
   @doc: "(switch- i v0 [v1 v2...]) - switch and pause multiple inputs
@@ -35,10 +37,16 @@ like (switch ...) except that the unused inputs are paused."
   setup: (@i, ...) =>
     @choices = { ... }
 
+    typ = @choices[1].type
+    for inp in *@choices[2,]
+      assert inp.type == typ, "not all values have the same type: #{typ} != #{inp.type}"
+
+    @out = Stream typ
+    @out
+
   update: (dt) =>
-    @i\update dt
-    i = @i\get!
-    active = switch @i\get!
+    i = @i\unwrap!
+    active = switch i
       when true
         @choices[1]
       when false
@@ -47,21 +55,18 @@ like (switch ...) except that the unused inputs are paused."
         i = 1 + (math.floor i) % #@choices
         @choices[i]
 
-    @value = if active
-      active\update dt
-      active\get!
+    @out\set if active
+      active\unwrap!
 
 class edge extends Op
   setup: (@i) =>
-    @value = false
     @last = false
+    @out = Stream @i.type
+    @out
 
   update: (dt) =>
-    @i\update dt
-
-    now = @i\get!
-
-    @value = not @last and now
+    now = @i\unwrap!
+    @out\set not @last and now
     @last = now
 
 class keep extends Op
@@ -71,12 +76,12 @@ always reproduces the last non-nil value the input produced or default.
 default defaults to zero."
 
   setup: (@i, @default=Const.num 0) =>
+    @out = Stream @i.type, @default.value
+    @out
 
   update: (dt) =>
-    @i\update dt
-
-    next = @i\get!
-    @value = next or @value or @default\get!
+    if next = @i\unwrap!
+      @out\set next
 
 {
   'switch': switch_