add types.T, fix spec + docs

37 files changed, 486 insertions, 428 deletions

diff --git a/alv-lib/logic.moon b/alv-lib/logic.moon
index 3c893df..c3cc66f 100644
--- a/alv-lib/logic.moon
+++ b/alv-lib/logic.moon
@@ -1,4 +1,4 @@
-import Op, ValueStream, Input, Error, val from require 'alv.base'
+import Op, SigStream, Constant, Input, Error, T, val from require 'alv.base'
 
 all_same = (first, list) ->
   for v in *list
@@ -17,7 +17,7 @@ tobool = (val) ->
 class ReduceOp extends Op
   pattern = val! + val! * 0
   setup: (inputs) =>
-    @out or= ValueStream 'bool'
+    @out or= SigStream T.bool
     { first, rest } = pattern\match inputs
     super
       first: Input.hot first
@@ -31,7 +31,7 @@ class ReduceOp extends Op
 
     @out\set accum
 
-eq = ValueStream.meta
+eq = Constant.meta
   meta:
     name: 'eq'
     summary: "Check for equality."
@@ -41,7 +41,7 @@ eq = ValueStream.meta
   value: class extends Op
     pattern = val! + val! * 0
     setup: (inputs) =>
-      @out or= ValueStream 'bool', false
+      @out or= SigStream T.bool, false
       { first, rest } = pattern\match inputs
       same = all_same first\type!, [i\type! for i in *rest]
 
@@ -68,7 +68,7 @@ eq = ValueStream.meta
 
       @out\set equal
 
-not_eq = ValueStream.meta
+not_eq = Constant.meta
   meta:
     name: 'not-eq'
     summary: "Check for inequality."
@@ -77,7 +77,7 @@ not_eq = ValueStream.meta
 
   value: class extends Op
     setup: (inputs) =>
-      @out or= ValueStream 'bool', false
+      @out or= SigStream T.bool, false
       assert #inputs > 1, Error 'argument', "need at least two values"
       super [Input.hot v for v in *inputs]
 
@@ -97,7 +97,7 @@ not_eq = ValueStream.meta
 
       @out\set diff
 
-and_ = ValueStream.meta
+and_ = Constant.meta
   meta:
     name: 'and'
     summary: "Logical AND."
@@ -105,7 +105,7 @@ and_ = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a and b
 
-or_ = ValueStream.meta
+or_ = Constant.meta
   meta:
     name: 'or'
     summary: "Logical OR."
@@ -113,7 +113,7 @@ or_ = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a or b
 
-not_ = ValueStream.meta
+not_ = Constant.meta
   meta:
     name: 'not'
     summary: "Logical NOT."
@@ -121,14 +121,14 @@ not_ = ValueStream.meta
 
   value: class extends Op
     setup: (inputs) =>
-      @out or= ValueStream 'bool', false
+      @out or= SigStream T.bool, false
       value = val!\match inputs
       super value: Input.hot value
 
     tick: =>
       @out\set not tobool @inputs.value!
 
-bool = ValueStream.meta
+bool = Constant.meta
   meta:
     name: 'bool'
     summary: "Cast value to bool."
@@ -137,7 +137,7 @@ bool = ValueStream.meta
 
   value: class extends Op
     setup: (inputs) =>
-      @out or= ValueStream 'bool'
+      @out or= SigStream T.bool
       value = val!\match inputs
       super value: Input.hot value
 
diff --git a/alv-lib/math.moon b/alv-lib/math.moon
index 2cf8e5d..8037e8a 100644
--- a/alv-lib/math.moon
+++ b/alv-lib/math.moon
@@ -1,10 +1,10 @@
-import Op, ValueStream, Error, Input, val from require 'alv.base'
+import Op, Constant, SigStream, Error, Input, T, val from require 'alv.base'
 unpack or= table.unpack
 
 class ReduceOp extends Op
   pattern = val.num + val.num*0
   setup: (inputs) =>
-    @out or= ValueStream 'num'
+    @out or= SigStream T.num
     { first, rest } = pattern\match inputs
     super
       first: Input.hot first
@@ -21,14 +21,16 @@ func_op = (func, pattern) ->
   class extends Op
 
     setup: (inputs) =>
-      @out or= ValueStream 'num'
+      @out or= SigStream T.num
+
       params = pattern\match inputs
       super [Input.hot p for p in *params]
 
+
     tick: => @out\set func unpack @unwrap_all!
 
 func_def = (name, args, func, summary, pattern) ->
-   ValueStream.meta
+   Constant.meta
      meta:
        :name
        :summary
@@ -39,17 +41,17 @@ evenodd_op = (remainder) ->
   class extends Op
     pattern = val.num + -val.num
     setup: (inputs) =>
-      @out or= ValueStream 'bool'
+      @out or= SigStream T.bool
       { val, div } = pattern\match inputs
       super
         val: Input.hot val
-        div: Input.hot div or ValueStream.num 2
+        div: Input.hot div or SigStream.num 2
 
     tick: =>
       { :val, :div } = @unwrap_all!
       @out\set (val % div) == remainder
 
-add = ValueStream.meta
+add = Constant.meta
   meta:
     name: 'add'
     summary: "Add values."
@@ -58,7 +60,7 @@ add = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a + b
 
-sub = ValueStream.meta
+sub = Constant.meta
   meta:
     name: 'sub'
     summary: "Subtract values."
@@ -67,7 +69,7 @@ sub = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a - b
 
-mul = ValueStream.meta
+mul = Constant.meta
   meta:
     name: 'mul'
     summary: "Multiply values."
@@ -75,7 +77,7 @@ mul = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a * b
 
-div = ValueStream.meta
+div = Constant.meta
   meta:
     name: 'div'
     summary: "Divide values."
@@ -84,7 +86,7 @@ div = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a / b
 
-pow = ValueStream.meta
+pow = Constant.meta
   meta:
     name: 'pow'
     summary: "Raise to a power."
@@ -93,7 +95,7 @@ pow = ValueStream.meta
   value: class extends ReduceOp
     fn: (a, b) -> a ^ b
 
-mod = ValueStream.meta
+mod = Constant.meta
   meta:
     name: 'mod'
     summary: 'Modulo operator.'
@@ -101,7 +103,7 @@ mod = ValueStream.meta
     description: "Calculate remainder of division by `div`."
   value: func_op ((a, b) -> a % b), val.num + val.num
 
-even = ValueStream.meta
+even = Constant.meta
   meta:
     name: 'even'
     summary: 'Check whether val is even.'
@@ -110,7 +112,7 @@ even = ValueStream.meta
 `div` defaults to 2."
   value: evenodd_op 0
 
-odd = ValueStream.meta
+odd = Constant.meta
   meta:
     name: 'odd'
     summary: 'Check whether val is odd.'
@@ -119,7 +121,7 @@ odd = ValueStream.meta
 `div` defaults to 2."
   value: evenodd_op 1
 
-mix = ValueStream.meta
+mix = Constant.meta
   meta:
     name: 'mix'
     summary: 'Linearly interpolate.'
@@ -127,7 +129,7 @@ mix = ValueStream.meta
     description: "Interpolate between `a` and `b` using `i` in range 0-1."
   value: func_op ((a, b, i) -> i*b + (1-i)*a), val.num + val.num + val.num
 
-min = ValueStream.meta
+min = Constant.meta
   meta:
     name: 'min'
     summary: "Find the minimum."
@@ -135,7 +137,7 @@ min = ValueStream.meta
     description: "Return the lowest of arguments."
   value: func_op math.min, val.num*0
 
-max = ValueStream.meta
+max = Constant.meta
   meta:
     name: 'max'
     summary: "Find the maximum."
@@ -176,12 +178,17 @@ sqrt = func_def 'sqrt', 'val', math.sqrt, "Square root function."
   :mix
   :min, :max
 
-  pi: with ValueStream.wrap math.pi
-    .meta = summary: 'The pi constant.'
-  tau: with ValueStream.wrap math.pi*2
-    .meta = summary: 'The tau constant.'
-  huge: with ValueStream.wrap math.huge
-    .meta = summary: 'Positive infinity constant.'
+  pi: Constant.meta
+    value: math.pi
+    meta: summary: 'The pi constant.'
+
+  tau: Constant.meta
+    value: math.pi*2
+    meta: summary: 'The tau constant.'
+
+  huge: Constant.meta
+    value: math.huge
+    meta: summary: 'Positive infinity constant.'
 
   :sin, :cos, :tan
   :asin, :acos, :atan, :atan2
diff --git a/alv-lib/midi.moon b/alv-lib/midi.moon
index 88d9547..e3bbe01 100644
--- a/alv-lib/midi.moon
+++ b/alv-lib/midi.moon
@@ -1,7 +1,7 @@
-import ValueStream, EventStream, Op, Input, val, evt from require 'alv.base'
+import Constant, Op, Input, T, val, evt from require 'alv.base'
 import input, output, inout, apply_range from require 'alv-lib.midi.core'
 
-gate = ValueStream.meta
+gate = Constant.meta
   meta:
     name: 'gate'
     summary: "gate from note-on and note-off messages."
@@ -10,12 +10,12 @@ gate = ValueStream.meta
   value: class extends Op
     pattern = -evt['midi/port'] + val.num -val.num
     setup: (inputs, scope) =>
-      @out or= ValueStream 'bool'
+      @out or= T.bool\mk_sig!
       { port, note, chan } = pattern\match inputs
       super
         port: Input.hot port or scope\get '*midi*'
         note: Input.hot note
-        chan: Input.hot chan or ValueStream.num -1
+        chan: Input.hot chan or Constant.num -1
 
     tick: =>
       { :port, :note, :chan } = @inputs
@@ -31,7 +31,7 @@ gate = ValueStream.meta
             elseif msg.status == 'note-off'
               @out\set false
 
-trig = ValueStream.meta
+trig = Constant.meta
   meta:
     name: 'trig'
     summary: "`bang`s from note-on messages."
@@ -40,12 +40,12 @@ trig = ValueStream.meta
   value: class extends Op
     pattern = -evt['midi/port'] + val.num -val.num
     setup: (inputs, scope) =>
-      @out or= EventStream 'bang'
+      @out or= T.bang\mk_evt!
       { port, note, chan } = pattern\match inputs
       super
         port: Input.hot port or scope\get '*midi*'
         note: Input.cold note
-        chan: Input.cold chan or ValueStream.num -1
+        chan: Input.cold chan or Constant.num -1
 
     tick: =>
       { :port, :note, :chan } = @inputs
@@ -55,7 +55,7 @@ trig = ValueStream.meta
           if msg.status == 'note-on'
             @out\add true
 
-cc = ValueStream.meta
+cc = Constant.meta
   meta:
     name: 'cc'
     summary: "`num` from cc-change messages."
@@ -76,10 +76,10 @@ cc = ValueStream.meta
       super
         port:  Input.hot port or scope\get '*midi*'
         cc:    Input.cold cc
-        chan:  Input.cold chan or ValueStream.num -1
-        range: Input.cold range or ValueStream.str 'uni'
+        chan:  Input.cold chan or Constant.num -1
+        range: Input.cold range or Constant.str 'uni'
 
-      @out or= ValueStream 'num', apply_range @inputs.range, 0
+      @out or= T.num\mk_sig apply_range @inputs.range, 0
 
     tick: =>
       { :port, :cc, :chan, :range } = @inputs
diff --git a/alv-lib/midi/core.moon b/alv-lib/midi/core.moon
index 3adc401..71d1e9f 100644
--- a/alv-lib/midi/core.moon
+++ b/alv-lib/midi/core.moon
@@ -1,4 +1,4 @@
-import ValueStream, IOStream, Op, Input, Error, val from require 'alv.base'
+import Constant, IOStream, Op, Input, T, Error, val from require 'alv.base'
 import RtMidiIn, RtMidiOut, RtMidi from require 'luartmidi'
 
 bit = do
@@ -31,7 +31,7 @@ find_port = (Klass, name) ->
     \openport id
 
 class MidiPort extends IOStream
-  new: => super 'midi/port'
+  new: => super T['midi/port']
 
   setup: (inp, out) =>
     @inp = inp and find_port RtMidiIn, inp
@@ -63,7 +63,7 @@ class PortOp extends Op
     { :inp, :out } = @unwrap_all!
     @out\setup inp, out
 
-input = ValueStream.meta
+input = Constant.meta
   meta:
     name: 'input'
     summary: "Create a MIDI input port."
@@ -74,7 +74,7 @@ input = ValueStream.meta
       name = val.str\match inputs
       super inp: Input.hot name
 
-output = ValueStream.meta
+output = Constant.meta
   meta:
     name: 'output'
     summary: "Create a MIDI output port."
@@ -85,7 +85,7 @@ output = ValueStream.meta
       name = val.str\match inputs
       super out: Input.hot name
 
-inout = ValueStream.meta
+inout = Constant.meta
   meta:
     name: 'inout'
     summary: "Create a bidirectional MIDI port."
@@ -99,7 +99,7 @@ inout = ValueStream.meta
         out: Input.hot out
 
 apply_range = (range, val) ->
-  if range\type! == 'str'
+  if range\type! == T.str
     switch range!
       when 'raw' then val
       when 'uni' then val / 128
@@ -108,7 +108,7 @@ apply_range = (range, val) ->
       when 'deg' then val / 128 * 360
       else
         error Error 'argument', "unknown range '#{range!}'"
-  elseif range.type == 'num'
+  elseif range.type == T.num
     val / 128 * range!
   else
     error Error 'argument', "range has to be a string or number"
diff --git a/alv-lib/midi/launchctl.moon b/alv-lib/midi/launchctl.moon
index 90e8956..3f47a5d 100644
--- a/alv-lib/midi/launchctl.moon
+++ b/alv-lib/midi/launchctl.moon
@@ -1,10 +1,10 @@
-import ValueStream, EventStream, Op, Input, val, evt from require 'alv.base'
+import Constant, Op, Input, T, val, evt from require 'alv.base'
 import apply_range, bit from require 'alv-lib.midi.core'
 import bor, lshift from bit
 
 color = (r, g) -> bit.bor 12, r, (bit.lshift g, 4)
 
-cc_seq = ValueStream.meta
+cc_seq = Constant.meta
   meta:
     name: 'cc-seq'
     summary: "MIDI CC-Sequencer."
@@ -32,11 +32,11 @@ range can be one of:
         i:     Input.hot i
         start: Input.hot start
         chan:  Input.hot chan
-        steps: Input.hot steps or ValueStream.num 8
-        range: Input.hot range or ValueStream.str 'uni'
+        steps: Input.hot steps or Constant.num 8
+        range: Input.hot range or Constant.str 'uni'
 
       @state or= {}
-      @out or= ValueStream 'num', apply_range @inputs.range, 0
+      @out or= T.num\mk_sig apply_range @inputs.range, 0
 
     tick: =>
       { :port, :i, :start, :chan, :steps, :range } = @inputs
@@ -60,7 +60,7 @@ range can be one of:
       else
         @out\set apply_range range, @state[curr_i+1]
 
-gate_seq = ValueStream.meta
+gate_seq = Constant.meta
   meta:
     name: 'gate-seq'
     summary: "MIDI Gate-Sequencer."
@@ -72,7 +72,7 @@ Send `true` or `false` for the `i`-th note-button (MIDI-notes starting from
   value: class extends Op
     pattern = -evt['midi/port'] + val.num + val.num + val.num + -val.num
     setup: (inputs, scope) =>
-      @out or= ValueStream 'bool'
+      @out or= T.bool\mk_sig!
       @state or= {}
       { port, i, start, chan, steps } = pattern\match inputs
 
@@ -81,7 +81,7 @@ Send `true` or `false` for the `i`-th note-button (MIDI-notes starting from
         i:     Input.hot i
         start: Input.hot start
         chan:  Input.hot chan
-        steps: Input.hot steps or ValueStream.num 8
+        steps: Input.hot steps or Constant.num 8
 
     light = (set, active) ->
       set = if set then 'S' else ' '
@@ -123,7 +123,7 @@ Send `true` or `false` for the `i`-th note-button (MIDI-notes starting from
 
         @out\set @state[curr_i+1]
 
-trig_seq = ValueStream.meta
+trig_seq = Constant.meta
   meta:
     name: 'trig-seq'
     summary: "MIDI Trigger-Sequencer."
@@ -135,7 +135,7 @@ Send bangs for the `i`-th note-button (MIDI-notes starting from `start`).
   value: class extends Op
     pattern = -evt['midi/port'] + val.num + val.num + val.num + -val.num
     setup: (inputs, scope) =>
-      @out or= EventStream 'bang'
+      @out or= T.bang\mk_evt!
       @state or= {}
       { port, i, start, chan, steps } = pattern\match inputs
 
@@ -144,7 +144,7 @@ Send bangs for the `i`-th note-button (MIDI-notes starting from `start`).
         i:     Input.hot i
         start: Input.hot start
         chan:  Input.hot chan
-        steps: Input.hot steps or ValueStream.num 8
+        steps: Input.hot steps or Constant.num 8
 
     light = (set, active) ->
       set = if set then 'S' else ' '
diff --git a/alv-lib/osc.moon b/alv-lib/osc.moon
index b7e25e7..bbf07a1 100644
--- a/alv-lib/osc.moon
+++ b/alv-lib/osc.moon
@@ -1,10 +1,10 @@
-import Op, ValueStream, Input, val, evt from require 'alv.base'
+import Op, Constant, SigStream, Input, T, val, evt from require 'alv.base'
 import pack from require 'osc'
 import dns, udp from require 'socket'
 
 unpack or= table.unpack
 
-connect = ValueStream.meta
+connect = Constant.meta
   meta:
     name: 'connect'
     summary: "Create a UDP remote."
@@ -13,7 +13,7 @@ connect = ValueStream.meta
   value: class extends Op
     pattern = val.str + val.num
     setup: (inputs) =>
-      @out or= ValueStream 'udp/socket'
+      @out or= SigStream T['udp/socket']
       { host, port } = pattern\match inputs
       super
         host: Input.hot host
@@ -26,7 +26,7 @@ connect = ValueStream.meta
       @out\set with sock = udp!
         \setpeername ip, port
 
-send = ValueStream.meta
+send = Constant.meta
   meta:
     name: 'send'
     summary: "Send events via OSC."
@@ -52,7 +52,7 @@ send = ValueStream.meta
         msg = pack path, if 'table' == type val then unpack val else val
         socket\send msg
 
-sync = ValueStream.meta
+sync = Constant.meta
   meta:
     name: 'sync'
     summary: "Synchronize a value via OSC."
diff --git a/alv-lib/pilot.moon b/alv-lib/pilot.moon
index 0d6eefb..e2103c6 100644
--- a/alv-lib/pilot.moon
+++ b/alv-lib/pilot.moon
@@ -1,4 +1,4 @@
-import Op, ValueStream, Input, val, evt from require 'alv.base'
+import Op, Constant, Input, val, evt from require 'alv.base'
 import udp from require 'socket'
 
 local conn
@@ -22,7 +22,7 @@ send = (...) ->
 
 arg = val.num / val.str
 
-play = ValueStream.meta
+play = Constant.meta
   meta:
     name: 'play'
     summary: "Play a note when a bang arrives."
@@ -41,7 +41,7 @@ play = ValueStream.meta
       for _ in *trig!
         send [a! for a in *@inputs.args]
 
-play_ = ValueStream.meta
+play_ = Constant.meta
   meta:
     name: 'play!'
     summary: "Play a note when a note arrives."
@@ -63,7 +63,7 @@ play_ = ValueStream.meta
       for note in *note!
         send { chan!, octv!, note }, args
 
-effect = ValueStream.meta
+effect = Constant.meta
   meta:
     name: 'effect'
     summary: "Set effect parameters."
diff --git a/alv-lib/random.moon b/alv-lib/random.moon
index 8c4d096..a2e4c60 100644
--- a/alv-lib/random.moon
+++ b/alv-lib/random.moon
@@ -1,7 +1,7 @@
-import ValueStream, Error, Op, Input, val, evt from require 'alv.base'
+import Constant, Error, Op, Input, T, Array, val, evt from require 'alv.base'
 
 apply_range = (range, val) ->
-  if range\type! == 'str'
+  if range\type! == T.str
     switch range!
       when 'uni' then val
       when 'bip' then val*2 - 1
@@ -9,7 +9,7 @@ apply_range = (range, val) ->
       when 'deg' then val * 360
       else
         error Error 'argument', "unknown range '#{range!}'"
-  elseif range\type! == 'num'
+  elseif range\type! == T.num
     val * range!
   else
     error Error 'argument', "range has to be a string or number"
@@ -24,7 +24,7 @@ range can be one of:
 
 pattern = -evt.bang + -(val.num / val.str)
 
-num = ValueStream.meta
+num = Constant.meta
   meta:
     name: 'num'
     summary: 'Generate a random number.'
@@ -35,7 +35,7 @@ num = ValueStream.meta
   value: class extends Op
     new: (...) =>
       super ...
-      @out or= ValueStream 'num'
+      @out or= T.num\mk_sig!
       @state or @gen!
 
     gen: => @state = math.random!
@@ -44,25 +44,26 @@ num = ValueStream.meta
       { trig, range } = pattern\match inputs
       super
         trig: trig and Input.hot trig
-        range: Input.hot range or ValueStream.str 'uni'
+        range: Input.hot range or Constant.str 'uni'
 
     tick: =>
       @gen! if @inputs.trig and @inputs.trig\dirty!
       @out\set apply_range @inputs.range, @state
 
 vec = (n) ->
-  ValueStream.meta
+  typ = Array n, T.num
+  Constant.meta
     meta:
       name: "vec#{n}"
       summary: 'Generate a random vector.'
       examples: { '(random/vec#{n} [trigger] [range]))' }
-      description: "Generate a random vec#{n} in `range` when created and on `trig`.
+      description: "Generate a random #{typ} in `range` when created and on `trig`.
 #{range_doc}"
 
     value: class extends Op
       new: (...) =>
         super ...
-        @out or= ValueStream "vec#{n}"
+        @out or= typ\mk_sig!
         @state or @gen!
 
       gen: => @state = for i=1,n do math.random!
@@ -71,9 +72,9 @@ vec = (n) ->
         { trig, range } = pattern\match inputs
         super
           trig: trig and Input.hot trig
-          range: Input.hot range or ValueStream.str 'uni'
+          range: Input.hot range or Constant.str 'uni'
 
-      tick: =>
+      tick: (setup) =>
         @gen! if @inputs.trig and @inputs.trig\dirty!
         @out\set [apply_range @inputs.range, v for v in *@state]
 
diff --git a/alv-lib/sc.moon b/alv-lib/sc.moon
index 2857392..7e4c711 100644
--- a/alv-lib/sc.moon
+++ b/alv-lib/sc.moon
@@ -1,10 +1,10 @@
-import Op, ValueStream, Input, val, evt from require 'alv.base'
+import Op, Constant, Input, val, evt from require 'alv.base'
 import pack from require 'osc'
 import dns, udp from require 'socket'
 
 unpack or= table.unpack
 
-play = ValueStream.meta
+play = Constant.meta
   meta:
     name: 'play'
     summary: 'Play a SuperCollider SynthDef on bangs.'
@@ -39,7 +39,7 @@ Plays the synth `synth` on the `udp/socket` `socket` whenever `trig` is live.
         msg = pack '/s_new', synth, -1, 0, 1, unpack ctrls
         socket\send msg
 
-play_ = ValueStream.meta
+play_ = Constant.meta
   meta:
     name: 'play!'
     summary: 'Play a SuperCollider SynthDef on events.'
diff --git a/alv-lib/string.moon b/alv-lib/string.moon
index 5f54b07..9f09f10 100644
--- a/alv-lib/string.moon
+++ b/alv-lib/string.moon
@@ -1,13 +1,13 @@
-import Op, ValueStream, Input from require 'alv.base'
+import Op, Constant, SigStream, Input, T from require 'alv.base'
 
-str = ValueStream.meta
+str = Constant.meta
   meta:
     name: 'str'
     summary: "Concatenate/stringify values."
     examples: { '(.. v1 [v2…])', '(str v1 [v2…])' }
   value: class extends Op
     setup: (inputs) =>
-      @out or= ValueStream 'str'
+      @out or= SigStream T.str
       super [Input.hot v for v in *inputs]
 
     tick: =>
diff --git a/alv-lib/time.moon b/alv-lib/time.moon
index ba7aa4a..86d7e4c 100644
--- a/alv-lib/time.moon
+++ b/alv-lib/time.moon
@@ -1,12 +1,10 @@
-import
-  ValueStream, EventStream, IOStream,
-  Error, Op, Input, val, evt
-from require 'alv.base'
+import Constant, EvtStream, IOStream, Error, Op, Input, T, val, evt
+  from require 'alv.base'
 import monotime from require 'system'
 
 class Clock extends IOStream
   new: (@frametime) =>
-    super 'clock'
+    super T.clock
 
     return unless monotime
     @last = monotime!
@@ -19,11 +17,11 @@ class Clock extends IOStream
       @add { dt: @dt, :time }
       @last = time
 
-class ScaledClock extends EventStream
+class ScaledClock extends EvtStream
   set: (val) => @value
   unwrap: => @value
 
-clock = ValueStream.meta
+clock = Constant.meta
   meta:
     name: 'clock'
     summary: "Create a clock source."
@@ -41,13 +39,13 @@ frame rate.
 
     setup: (inputs) =>
       fps = (-val.num)\match inputs
-      super fps: Input.hot fps or ValueStream.num 60
+      super fps: Input.hot fps or Constant.num 60
       @out.frametime = 1 / @inputs.fps!
 
     tick: =>
       @out.frametime = 1 / @inputs.fps!
 
-scale_time = ValueStream.meta
+scale_time = Constant.meta
   meta:
     name: 'scale-time'
     summary: "Scale clock time."
@@ -60,7 +58,7 @@ scale_time = ValueStream.meta
   value: class extends Op
     new: (...) =>
       super ...
-      @out or= EventStream 'clock'
+      @out or= EvtStream T.clock
 
     pattern = -evt.clock + val.num + -val.str
     setup: (inputs, scope) =>
@@ -74,7 +72,7 @@ scale_time = ValueStream.meta
       for evt in *@inputs.clock!
         @out\add {k, v*scale for k,v in pairs evt}
 
-lfo = ValueStream.meta
+lfo = Constant.meta
   meta:
     name: 'lfo'
     summary: "Low-frequency oscillator."
@@ -92,9 +90,9 @@ lfo = ValueStream.meta
     new: (...) =>
       super ...
       @state or= 0
-      @out or= ValueStream 'num'
+      @out or= T.num\mk_sig!
 
-    default_wave = ValueStream.str 'sin'
+    default_wave = Constant.str 'sin'
     pattern = -evt.clock + val.num + -val.str
     setup: (inputs, scope) =>
       { clock, freq, wave } = pattern\match inputs
@@ -114,7 +112,7 @@ lfo = ValueStream.meta
         when 'tri' then math.abs (2*@state % 2) - 1
         else error Error 'argument', "unknown wave type '#{wave}'"
 
-ramp = ValueStream.meta
+ramp = Constant.meta
   meta:
     name: 'ramp'
     summary: "Sawtooth LFO."
@@ -129,7 +127,7 @@ ramp = ValueStream.meta
     new: (...) =>
       super ...
       @state or= 0
-      @out or= ValueStream 'num'
+      @out or= T.num\mk_sig!
 
     pattern = -evt.clock + val.num + -val.num
     setup: (inputs, scope) =>
@@ -150,7 +148,7 @@ ramp = ValueStream.meta
 
       @out\set @phase * max
 
-tick = ValueStream.meta
+tick = Constant.meta
   meta:
     name: 'tick'
     summary: "Count ticks."
@@ -165,7 +163,7 @@ tick = ValueStream.meta
     new: (...) =>
       super ...
       @state or= { phase: 0, count: 0 }
-      @out or= ValueStream 'num', @state.count
+      @out or= T.num\mk_sig! @state.count
 
     pattern = -evt.clock + val.num
     setup: (inputs, scope) =>
@@ -183,7 +181,7 @@ tick = ValueStream.meta
         @state.count += 1
         @out\set @state.count
 
-every = ValueStream.meta
+every = Constant.meta
   meta:
     name: 'every'
     summary: "Emit events regularly."
@@ -206,8 +204,8 @@ every = ValueStream.meta
       super
         clock: Input.hot clock or scope\get '*clock*'
         period: Input.cold period
-        evt: Input.cold evt or ValueStream 'bang', true
-      @out = EventStream @inputs.evt\type!
+        evt: Input.cold evt or Constant.bang, true
+      @out = @inputs.evt\type!\mk_evt!
 
     tick: =>
       for tick in *@inputs.clock!
@@ -217,7 +215,7 @@ every = ValueStream.meta
         @state -= 1
         @out\add @inputs.evt!
 
-sequence = ValueStream.meta
+sequence = Constant.meta
   meta:
     name: 'sequence'
     summary: "Emit a sequence of values as events over time."
@@ -246,7 +244,7 @@ Emits `evt1`, `evt2`, … as events with delays `delay0`, `delay1`, … in betwe
 
     setup: (inputs, scope) =>
       { clock, first, steps } = pattern\match inputs
-      @out = EventStream steps[1].value\type!
+      @out = EvtStream steps[1].value\type!
       table.insert steps, 1, { delay: first }
       super
         clock: Input.hot clock or scope\get '*clock*'
diff --git a/alv-lib/util.moon b/alv-lib/util.moon
index abb49c0..512d74d 100644
--- a/alv-lib/util.moon
+++ b/alv-lib/util.moon
@@ -1,4 +1,4 @@
-import Op, ValueStream, EventStream, Input, val, evt from require 'alv.base'
+import Constant, Op, Input, T, val, evt from require 'alv.base'
 
 all_same = (list) ->
   for v in *list[2,]
@@ -7,7 +7,7 @@ all_same = (list) ->
 
   list[1]
 
-switch_ = ValueStream.meta
+switch_ = Constant.meta
   meta:
     name: 'switch'
     summary: "Switch between multiple inputs."
@@ -24,12 +24,12 @@ switch_ = ValueStream.meta
     setup: (inputs) =>
       { i, values } = pattern\match inputs
 
-      @state = values[1].value.__class == ValueStream
+      @state = values[1].value.metatype == '~'
 
       @out = if @state
-        ValueStream values[1]\type!
+        values[1]\type!\mk_sig!
       else
-        EventStream values[1]\type!
+        values[1]\type!\mk_evt!
 
       super
         i: Input.hot i
@@ -52,7 +52,7 @@ switch_ = ValueStream.meta
           for event in *active!
             @out\add event
 
-edge = ValueStream.meta
+edge = Constant.meta
   meta:
     name: 'edge'
     summary: "Convert rising edges to bangs."
@@ -60,7 +60,7 @@ edge = ValueStream.meta
 
   value: class extends Op
     setup: (inputs) =>
-      @out or= EventStream 'bang'
+      @out or= T.bang\mk_evt!
       value = val.bool\match inputs
       super value: Input.hot value
 
@@ -70,7 +70,7 @@ edge = ValueStream.meta
         @out\add true
       @state = now
 
-change = ValueStream.meta
+change = Constant.meta
   meta:
     name: 'change'
     summary: "Convert value changes to events."
@@ -79,7 +79,7 @@ change = ValueStream.meta
   value: class extends Op
     setup: (inputs) =>
       value = val!\match inputs
-      @out or= EventStream value\type!
+      @out or= value\type!\mk_evt!
       super value: Input.hot value
 
     tick: =>
@@ -88,7 +88,7 @@ change = ValueStream.meta
         @out\add @inputs.value!
         @state = now
 
-hold = ValueStream.meta
+hold = Constant.meta
   meta:
     name: 'hold'
     summary: "Convert events to value changes."
@@ -97,7 +97,7 @@ hold = ValueStream.meta
   value: class extends Op
     setup: (inputs) =>
       event = evt!\match inputs
-      @out or= ValueStream event\type!
+      @out or= event\type!\mk_sig!
       super event: Input.hot event
 
     tick: =>
diff --git a/alv/base/init.moon b/alv/base/init.moon
index 62de2ab..90f1dfc 100644
--- a/alv/base/init.moon
+++ b/alv/base/init.moon
@@ -15,6 +15,10 @@
 -- @see SigStream
 -- @see EvtStream
 -- @see IOStream
+-- @see type.T
+-- @see type.Primitive
+-- @see type.Array
+-- @see type.Struct
 -- @see RTNode
 -- @see Error
 
@@ -24,7 +28,7 @@ import FnDef from require 'alv.base.fndef'
 import Input from require 'alv.base.input'
 import val, evt from require 'alv.base.match'
 import Constant, SigStream, EvtStream, IOStream from require 'alv.result'
-import Primitive, Array, Struct from require 'alv.type'
+import T, Primitive, Array, Struct from require 'alv.type'
 import RTNode from require 'alv.rtnode'
 import Error from require 'alv.error'
 
@@ -41,7 +45,7 @@ import Error from require 'alv.error'
   :Constant, :SigStream, :EvtStream, :IOStream
 
   -- Types
-  :Primitive, :Array, :Struct
+  :T, :Primitive, :Array, :Struct
 
   :RTNode
   :Error
diff --git a/alv/base/input.moon b/alv/base/input.moon
index a9f0e32..b73a476 100644
--- a/alv/base/input.moon
+++ b/alv/base/input.moon
@@ -35,9 +35,9 @@ class Input
   --- create a new Input.
   --
   -- @classmethod
-  -- @tparam Result stream
-  new: (@stream) =>
-    assert @stream, "nil passed to Input: #{value}"
+  -- @tparam Result result
+  new: (@result) =>
+    assert @result, "nil passed to Input: #{value}"
 
   --- copy state from old instance (optional).
   --
@@ -53,10 +53,10 @@ class Input
   --
   -- must return a boolean indicating whether `Op`s that refer to this instance
   -- should be notified (via `Op:tick`). If not overwritten, delegates to
-  -- `stream`:@{SigStream:dirty|dirty}.
+  -- `result`:@{SigStream:dirty|dirty}.
   --
   -- @treturn bool whether processing is necessary
-  dirty: => @stream\dirty!
+  dirty: => @result\dirty!
 
   --- leave setup state (optional).
   --
@@ -67,25 +67,25 @@ class Input
   --- unwrap to Lua value (optional).
   --
   -- @treturn any the raw Lua value
-  unwrap: => @stream\unwrap!
+  unwrap: => @result\unwrap!
 
   --- return the type name of this `Input` (optional).
-  type: => @stream.type
+  type: => @result.type
 
   --- return the metatype name of this `Input` (optional).
-  metatype: => @stream.metatype
+  metatype: => @result.metatype
 
   --- the current value
   --
-  -- @tfield SigStream stream
+  -- @tfield SigStream result
 
 --- members
 -- @section members
 
   --- alias for `unwrap`.
-  __call: => @stream\unwrap!
+  __call: => @result\unwrap!
 
-  __tostring: => "#{@@__name}:#{@stream}"
+  __tostring: => "#{@@__name}:#{@result}"
   __inherited: (cls) =>
     cls.__base.__call = @__call
     cls.__base.__tostring = @__tostring
@@ -95,7 +95,7 @@ class Input
 
   --- Create a `cold` `Input`.
   --
-  -- Never marked dirty. Use this for input streams that are only read when
+  -- Never marked dirty. Use this for input results that are only read when
   -- another `Input` is dirty.
   --
   -- @tparam Result|RTNode value
@@ -128,17 +128,17 @@ class ColdInput extends Input
   dirty: => false
 
 class ValueInput extends Input
-  setup: (old) => @dirty_setup = not old or @stream != old.stream
+  setup: (old) => @dirty_setup = not old or @result != old.result
   finish_setup: => @dirty_setup = nil
   dirty: =>
     return @dirty_setup if @dirty_setup != nil
-    @stream\dirty!
+    @result\dirty!
 
 class IOInput extends Input
   io: true
 
 mapping = {
-  [Constant]: ColdInput
+  [Constant]: ValueInput
   [SigStream]: ValueInput
   [EvtStream]: Input
   [IOStream]: IOInput
diff --git a/alv/builtin.moon b/alv/builtin.moon
index 29602e2..45ee626 100644
--- a/alv/builtin.moon
+++ b/alv/builtin.moon
@@ -5,7 +5,7 @@
 -- documentation.
 --
 -- @module builtin
-import Builtin, Op, Primitive, FnDef, Input, val, evt from require 'alv.base'
+import Builtin, Op, T, FnDef, Input, val, evt from require 'alv.base'
 import Constant from require 'alv.result'
 import Error from require 'alv.error'
 import RTNode from require 'alv.rtnode'
@@ -58,7 +58,7 @@ Define the symbols `sym1`, `sym2`, … to resolve to the values of `val-expr1`,
       children = L\push ->
         return for i=1,#tail,2
           name, val_expr = tail[i], tail[i+1]
-          name = name\unwrap 'sym'
+          name = name\unwrap T.sym
 
           with val_expr\eval scope
             scope\set name, \make_ref!
@@ -117,7 +117,7 @@ current scope."
       assert #tail > 0, "'import' requires at least one arguments"
 
       children = for i, child in ipairs tail
-        name = child\unwrap 'sym'
+        name = child\unwrap T.sym
         with COPILOT\require name
           scope\set name, \make_ref!
       RTNode :children
@@ -136,8 +136,8 @@ Requires modules `sym1`, `sym2`, … and merges them into the current scope."
       assert #tail > 0, "'import' requires at least one arguments"
 
       children = for i, child in ipairs tail
-        with COPILOT\require child\unwrap 'sym'
-          scope\use .value\unwrap 'scope'
+        with COPILOT\require child\unwrap T.sym
+          scope\use .result\unwrap T.scope
       RTNode :children
 
 export_ = Constant.meta
@@ -175,7 +175,7 @@ Copies the containing scope if no symbols are given."
           node
       else
         for child in *tail
-          name = child\unwrap 'sym'
+          name = child\unwrap T.sym
           with node = scope\get name
             new_scope\set name, node
 
@@ -198,7 +198,7 @@ function is invoked."
 
       assert params.__class == Cell, "'fn's first argument has to be an expression"
       param_symbols = for param in *params.children
-        assert param.type == 'sym', "function parameter declaration has to be a symbol"
+        assert param.type == T.sym, "function parameter declaration has to be a symbol"
         param
 
       RTNode result: with Constant.wrap FnDef param_symbols, body, scope
@@ -223,10 +223,10 @@ function is invoked."
       assert #tail == 3, "'defn' takes exactly three arguments"
       { name, params, body } = tail
 
-      name = name\unwrap 'sym'
+      name = name\unwrap T.sym
       assert params.__class == Cell, "'defn's second argument has to be an expression"
       param_symbols = for param in *params.children
-        assert param.type == 'sym', "function parameter declaration has to be a symbol"
+        assert param.type == T.sym, "function parameter declaration has to be a symbol"
         param
 
       result = with Constant.wrap FnDef param_symbols, body, scope
@@ -305,7 +305,7 @@ trace = Constant.meta
           value: Input.hot inputs[2]
 
       tick: =>
-        L\print "trace #{@inputs.prefix!}: #{@inputs.value.stream}"
+        L\print "trace #{@inputs.prefix!}: #{@inputs.value\type!\pp @inputs.value!}"
 
     eval: (scope, tail) =>
       L\trace "evaling #{@}"
@@ -313,7 +313,7 @@ trace = Constant.meta
 
       tag = @tag\clone Tag.parse '-1'
       inner = Cell tag, {
-        Constant.literal Primitive.op, traceOp, 'trace'
+        Constant.literal T.opdef, traceOp, 'trace'
         Constant.str tostring tail[1]
         tail[1]
       }
@@ -364,7 +364,7 @@ Scope.from_table {
     meta:
       name: 'bang'
       summary: "A `bang` value-constant."
-    value: Constant 'bang', true
+    value: Constant T.bang, true
 
   :fn, :defn
   'do': do_expr
diff --git a/alv/cell.moon b/alv/cell.moon
index 759e7aa..36d5f43 100644
--- a/alv/cell.moon
+++ b/alv/cell.moon
@@ -5,7 +5,7 @@
 -- nodes), a `Tag`, and optionally the internal whitespace as parsed.
 --
 -- @classmod Cell
-import Primitive from require 'alv.type'
+import T from require 'alv.type'
 import Constant from require 'alv.result'
 import Error from require 'alv.error'
 import op_invoke, fn_invoke from require 'alv.invoke'
@@ -74,11 +74,11 @@ class Cell
     head = assert @head!, Error 'syntax', "cannot evaluate empty expr"
     head = (head\eval scope)\const!
     Builtin = switch head.type
-      when Primitive.op
+      when T.opdef
         op_invoke
-      when Primitive.fn
+      when T.fndef
         fn_invoke
-      when Primitive.builtin
+      when T.builtin
         head\unwrap!
       else
         error Error 'type', "#{head} is not an opdef, fndef or builtin"
diff --git a/alv/copilot.moon b/alv/copilot.moon
index 55e00c8..e6eb293 100644
--- a/alv/copilot.moon
+++ b/alv/copilot.moon
@@ -53,7 +53,7 @@ class Copilot
           mod.root\make_ref!
         else
           last = @active_module
-          prefix = @active_module.file\match('(.*)/[^/]*$') .. '/' or ''
+          prefix = if b = last.file\match'(.*)/[^/]*$' then b .. '/' else ''
           mod = @last_modules[name] or Module "#{prefix}#{name}.alv"
           L\trace "entering module #{mod}"
           @modules[name] = mod
diff --git a/alv/error.moon b/alv/error.moon
index e72cc5f..c049f8f 100644
--- a/alv/error.moon
+++ b/alv/error.moon
@@ -48,7 +48,9 @@ class Error
     if err.__class == Error
       err
     else
-      Error 'implementation', err, debug.traceback "Lua error below:", 2
+      trace = debug.traceback "Lua error below:", 2
+      Error 'implementation', err, trace
+
   --- Wrap function errors in a traceback frame.
   --
   -- Execute `fn(...)`, and turn any error thrown as a result into an
@@ -65,8 +67,8 @@ class Error
     if ok
       unpack results
     else
-      error with results[1]
-        \add_frame frame
+      results[1]\add_frame frame if frame
+      error results[1]
 
   --- Capture and wrap function errors in traceback frame.
   --
@@ -76,7 +78,7 @@ class Error
   -- When `Error` instances are caught, `frame` is added to the traceback.
   -- All other error values are turned into `'implementation'` Errors.
   --
-  -- @tparam string frame
+  -- @tparam ?string frame
   -- @tparam function fn
   -- @treturn boolean `ok` true if exeuction suceeded without errors
   -- @treturn Error|any `error_or_results` the `Error` instance or results
@@ -86,9 +88,8 @@ class Error
     if ok
       ok, unpack results
     else
-      ok, with results[1]
-        \add_frame frame
-
+      results[1]\add_frame frame if frame
+      ok, unpack results
 {
   :Error
 }
diff --git a/alv/init.moon b/alv/init.moon
index ec90a10..fc85f8b 100644
--- a/alv/init.moon
+++ b/alv/init.moon
@@ -14,7 +14,7 @@ cycle = require 'alv.cycle'
 version = require 'alv.version'
 import Logger from require 'alv.logger'
 
-import Primitive, Struct, Array from require 'alv.type'
+import T, Primitive, Struct, Array from require 'alv.type'
 import Constant, SigStream, EvtStream, IOStream from require 'alv.result'
 import RTNode from require 'alv.rtnode'
 import Scope from require 'alv.scope'
@@ -40,6 +40,10 @@ import Copilot from require 'alv.copilot'
 -- @tfield SigStream SigStream
 -- @tfield EvtStream EvtStream
 -- @tfield IOStream IOStream
+-- @tfield type.T T
+-- @tfield type.Primitive Primitive
+-- @tfield type.Array Array
+-- @tfield type.Struct Struct
 -- @tfield RTNode RTNode
 -- @tfield Cell Cell
 -- @tfield RootCell RootCell
@@ -58,7 +62,7 @@ import Copilot from require 'alv.copilot'
   :Cell, :RootCell
   :RTNode, :Scope, :Error
 
-  :Primitive, :Struct, :Array
+  :T, :Primitive, :Struct, :Array
 
   :Registry, :SimpleRegistry, :Tag
 
diff --git a/alv/invoke.moon b/alv/invoke.moon
index 390e19f..9acb77c 100644
--- a/alv/invoke.moon
+++ b/alv/invoke.moon
@@ -5,7 +5,7 @@
 import RTNode from require 'alv.rtnode'
 import Builtin from require 'alv.base'
 import Scope from require 'alv.scope'
-import Primitive from require 'alv.type'
+import T from require 'alv.type'
 import Error from require 'alv.error'
 
 get_name = (value, raw) ->
@@ -35,14 +35,14 @@ class op_invoke extends Builtin
       @op = prev.op\fork!
       prev.forked = COPILOT.T
     else
-      def = @head\unwrap Primitive.opdef, "cant op-invoke #{@head}"
+      def = @head\unwrap T.opdef, "cant op-invoke #{@head}"
       @op = def!
 
   --- `Builtin:destroy` implementation.
   --
   -- calls `op`:@{Op:destroy|destroy}.
   destroy: =>
-    if @forked ~= COPILOT.T
+    if @op and @forked ~= COPILOT.T
       @op\destroy!
 
   --- perform an `Op` invocation.
@@ -60,19 +60,20 @@ class op_invoke extends Builtin
     children = [L\push expr\eval, scope for expr in *tail]
 
     frame = "invoking op #{get_name @head, @cell\head!} at [#{@tag}]"
-    Error.wrap frame, @op\setup, [node for node in *children], scope
+    Error.wrap frame, ->
+      @op\setup [node for node in *children], scope
 
-    any_dirty = false
-    for input in @op\all_inputs!
-      if input\dirty!
-        any_dirty = true
-        break
+      any_dirty = false
+      for input in @op\all_inputs!
+        if input\dirty!
+          any_dirty = true
+          break
 
-    if any_dirty
-      @op\tick true
+      if any_dirty
+        @op\tick true
 
-    for input in @op\all_inputs!
-      input\finish_setup!
+      for input in @op\all_inputs!
+        input\finish_setup!
 
     RTNode :children, result: @op.out, op: @op
 
@@ -104,7 +105,7 @@ class fn_invoke extends Builtin
     name = get_name @head, @cell\head!
     frame = "invoking function #{name} at [#{@tag}]"
 
-    fndef = @head\unwrap Primitive.fndef, "cant fn-invoke #{@head}"
+    fndef = @head\unwrap T.fndef, "cant fn-invoke #{@head}"
     { :params, :body } = fndef
     if #params != #tail
       err = Error 'argument', "expected #{#params} arguments, found #{#tail}"
@@ -114,7 +115,7 @@ class fn_invoke extends Builtin
     fn_scope = Scope fndef.scope, caller_scope
 
     children = for i=1,#params
-      name = params[i]\unwrap Primitive.sym
+      name = params[i]\unwrap T.sym
       with L\push tail[i]\eval, caller_scope
         fn_scope\set name, \make_ref!
 
diff --git a/alv/module.moon b/alv/module.moon
index 7179ab6..0e95593 100644
--- a/alv/module.moon
+++ b/alv/module.moon
@@ -34,7 +34,7 @@ class Module
   -- @treturn bool whether the file was changed since the last call
   poll: =>
     { :mode, :modification } = (lfs.attributes @file) or {}
-    assert mode == 'file', Error 'io', "not a file: '#{file}'"
+    assert mode == 'file', Error 'io', "not a file: '#{@file}'"
     modification
 
   --- start an evaluation cycle.
diff --git a/alv/result/base.moon b/alv/result/base.moon
index 6accb1e..7775349 100644
--- a/alv/result/base.moon
+++ b/alv/result/base.moon
@@ -24,7 +24,11 @@ class Result
   -- @function fork
   -- @treturn Result
 
-  __tostring: => "<#{@type}#{@metatype} #{@type\pp @value}>"
+  __tostring: =>
+    if @value then
+      "<#{@type}#{@metatype} #{@type\pp @value}>"
+    else
+      "<#{@type}#{@metatype}>"
   __inherited: (cls) => cls.__base.__tostring or= @__tostring
 
   --- the type of this Result's value.
@@ -56,12 +60,14 @@ class Result
 --- static functions
 -- @section static
 
+  _type = type
   --- construct a new Result.
   --
   -- @classmethod
   -- @tparam type.Type type the type
   -- @tparam ?table meta the `meta` table
   new: (@type, @meta={}) =>
+    assert @type and (_type @type) == 'table', "not a type: #{@type}"
 
 {
   :Result
diff --git a/alv/result/const.moon b/alv/result/const.moon
index b88de2c..077a2d8 100644
--- a/alv/result/const.moon
+++ b/alv/result/const.moon
@@ -5,16 +5,11 @@
 --
 -- @classmod Constant
 import Result from require 'alv.result.base'
-import Primitive from require 'alv.type'
+import T from require 'alv.type'
 import RTNode from require 'alv.rtnode'
 import Error from require 'alv.error'
 import scope, base from require 'alv.cycle'
 
-num = Primitive 'num'
-str = Primitive 'str'
-sym = Primitive 'sym'
-bool = Primitive 'bool'
-
 ancestor = (klass) ->
   assert klass, "cant find the ancestor of nil"
   while klass.__parent
@@ -78,9 +73,9 @@ class Constant extends Result
     return RTNode result: @ if @literal
 
     switch @type
-      when num, str
+      when T.num, T.str
         RTNode result: @
-      when sym
+      when T.sym
         Error.wrap "resolving symbol '#{@value}'", scope\get, @value
       else
         error "cannot evaluate #{@}"
@@ -106,7 +101,9 @@ class Constant extends Result
   -- @tparam string type the type name
   -- @tparam any value the Lua value to be accessed through `unwrap`
   -- @tparam string raw the raw string that resulted in this value. Used by `parsing`.
-  new: (type, @value, @raw) => super type
+  new: (type, @value, @raw) =>
+    super type
+    assert @value ~= nil, "Constant without value"
 
   unescape = (str) -> str\gsub '\\([\'"\\])', '%1'
   --- create a capture-function (for parsing with Lpeg).
@@ -115,9 +112,9 @@ class Constant extends Result
   -- @tparam string sep the seperator char (only for `str`)
   @parse: (type, sep) =>
     switch type
-      when 'num' then (match) -> @ num, (tonumber match), match
-      when 'sym' then (match) -> @ sym, match, match
-      when 'str' then (match) -> @ str, (unescape match), sep .. match .. sep
+      when 'num' then (match) -> @ T.num, (tonumber match), match
+      when 'sym' then (match) -> @ T.sym, match, match
+      when 'str' then (match) -> @ T.str, (unescape match), sep .. match .. sep
 
   --- wrap a Lua value.
   --
@@ -128,28 +125,28 @@ class Constant extends Result
   -- @treturn Constant
   @wrap: (val, name='(unknown)') ->
     typ = switch type val
-      when 'number' then Primitive.num
-      when 'string' then Primitive.str
+      when 'number' then T.num
+      when 'string' then T.str
       when 'table'
         if rawget val, '__base'
           -- a class
           switch ancestor val
-            when base.Op then Primitive.op
-            when base.Builtin then Primitive.builtin
+            when base.Op then T.opdef
+            when base.Builtin then T.builtin
             else
               error "#{name}: cannot wrap class '#{val.__name}'"
         elseif val.__class
           -- an instance
           switch ancestor val.__class
-            when scope.Scope then Primitive.scope
-            when base.FnDef then Primitive.fn
+            when scope.Scope then T.scope
+            when base.FnDef then T.fndef
             when Result then return val
             else
               error "#{name}: cannot wrap '#{val.__class.__name}' instance"
         else
           -- plain table
           val = scope.Scope.from_table val
-          Primitive.scope
+          T.scope
       else
         error "#{name}: cannot wrap Lua type '#{type val}'"
 
@@ -158,22 +155,22 @@ class Constant extends Result
   --- create a constant number.
   -- @tparam number num the number
   -- @treturn Constant
-  @num: (num) -> Constant Primitive.num, num, tostring num
+  @num: (num) -> Constant T.num, num, tostring num
 
   --- create a constant string.
   -- @tparam string str the string
   -- @treturn Constant
-  @str: (str) -> Constant Primitive.str, str, "'#{str}'"
+  @str: (str) -> Constant T.str, str, "'#{str}'"
 
   --- create a constant symbol.
   -- @tparam string sym the symbol
   -- @treturn Constant
-  @sym: (sym) -> Constant Primitive.sym, sym, sym
+  @sym: (sym) -> Constant T.sym, sym, sym
 
   --- create a constant boolean.
   -- @tparam boolean bool the boolean
   -- @treturn Constant
-  @bool: (bool) -> Constant Primitive.bool, bool, tostring bool
+  @bool: (bool) -> Constant T.bool, bool, tostring bool
 
   --- create a forced-literal Constant.
   --
diff --git a/alv/result/evt.moon b/alv/result/evt.moon
index bab502c..7e6a249 100644
--- a/alv/result/evt.moon
+++ b/alv/result/evt.moon
@@ -35,7 +35,10 @@ class EvtStream extends Result
 
   --- alias for `unwrap`.
   __call: (...) => @unwrap ...
-  __tostring: => "<#{@type}#{@metatype} #{@type\pp @value}>"
+
+  __tostring: =>
+    events = table.concat [@type\pp e for e in *@events], ' '
+    "<#{@type}#{@metatype} #{events}>"
 
   --- the type of this Result's value.
   -- @tfield type.Type type
@@ -79,7 +82,9 @@ class EvtStream extends Result
   --
   -- @classmethod
   -- @tparam type.Type type the type
-  new: (type) => super type
+  new: (type) =>
+    super type
+    @events = {}
 
 {
   :EvtStream
diff --git a/alv/result/sig.moon b/alv/result/sig.moon
index 73f06d1..b23afbe 100644
--- a/alv/result/sig.moon
+++ b/alv/result/sig.moon
@@ -3,7 +3,6 @@
 --
 -- @classmod SigStream
 import Result from require 'alv.result.base'
-import Primitive from require 'alv.type'
 
 class SigStream extends Result
 --- Result interface
@@ -79,33 +78,13 @@ class SigStream extends Result
 --- static functions
 -- @section static
 
-  --- construct a new SigStream.
+  --- construct a new Constant.
   --
   -- @classmethod
-  -- @tparam type.Type type the type
-  -- @tparam any value the Lua value to be accessed through `unwrap`
+  -- @tparam string type the type name
+  -- @tparam ?any value the Lua value to be accessed through `unwrap`
   new: (type, @value) => super type
 
-  --- create a number stream.
-  -- @tparam number val the number
-  -- @treturn SigStream
-  @num: (val) -> SigStream Primitive'num', val
-
-  --- create a string stream.
-  -- @tparam string val the string
-  -- @treturn SigStream
-  @str: (val) -> SigStream Primitive'str', val
-
-  --- create a symbol stream.
-  -- @tparam string val the symbol
-  -- @treturn symbol
-  @sym: (val) -> SigStream Primitive'sym', val
-
-  --- create a boolean stream.
-  -- @tparam boolean val the boolean
-  -- @treturn SigStream
-  @bool: (val) -> SigStream Primitive'bool', val
-
 {
   :SigStream
 }
diff --git a/alv/rtnode.moon b/alv/rtnode.moon
index a8ebec3..61222ef 100644
--- a/alv/rtnode.moon
+++ b/alv/rtnode.moon
@@ -5,6 +5,9 @@
 -- between `Op`s.
 --
 -- @classmod RTNode
+
+import Error from require 'alv.error'
+
 class RTNode
 --- members
 -- @section members
@@ -41,15 +44,15 @@ class RTNode
   --- poll all IOStream instances that are effecting this (sub)tree.
   -- should be called once per frame on the root, right before tick.
   poll_io: =>
-    for stream, input in pairs @side_inputs
-      stream\poll! if input.io
+    for result, input in pairs @side_inputs
+      result\poll! if input.io
 
   --- in depth-first order, tick all Ops which have dirty Inputs.
   --
   -- short-circuits if there are no dirty Inputs in the entire subtree
   tick: =>
     any_dirty = false
-    for stream, input in pairs @side_inputs
+    for result, input in pairs @side_inputs
       if input\dirty!
         any_dirty = true
         break
@@ -70,7 +73,7 @@ class RTNode
 
       return unless self_dirty
 
-      @op\tick!
+      Error.wrap "ticking #{op}", @op\tick
 
   __tostring: =>
     buf = "<RT=#{@result}"
@@ -111,15 +114,15 @@ class RTNode
 
     @side_inputs, is_child = {}, {}
     for child in *@children
-      for stream, input in pairs child.side_inputs
-        @side_inputs[stream] = input
+      for result, input in pairs child.side_inputs
+        @side_inputs[result] = input
       if child.result
         is_child[child.result] = true
 
     if @op
       for input in @op\all_inputs!
-        if input.io or not is_child[input.stream]
-          @side_inputs[input.stream] = input
+        if input.io or not is_child[input.result]
+          @side_inputs[input.result] = input
 
     if @result and @result.metatype == '='
       assert not (next @side_inputs), "Const result has side_inputs"
diff --git a/alv/scope.moon b/alv/scope.moon
index b150280..4adf07d 100644
--- a/alv/scope.moon
+++ b/alv/scope.moon
@@ -5,7 +5,7 @@
 import Constant from require 'alv.result'
 import RTNode from require 'alv.rtnode'
 import Error from require 'alv.error'
-import Primitive from require 'alv.type'
+import T from require 'alv.type'
 
 class Scope
 --- members
@@ -57,7 +57,7 @@ class Scope
     child = @get start
     if not child
       error Error 'reference', "undefined symbol '#{start}'"
-    if child\type! != Primitive.scope
+    if child\type! != T.scope
       error Error 'reference', "'#{start}' is not a scope"
     child.result!\get rest, while_msg
 
diff --git a/alv/type.moon b/alv/type.moon
index 8a3708b..5c76b86 100644
--- a/alv/type.moon
+++ b/alv/type.moon
@@ -3,6 +3,7 @@
 --
 -- @module type
 import opairs from require 'alv.util'
+import result from require 'alv.cycle'
 
 shared_shape = (a, b) ->
   for key in pairs a
@@ -20,74 +21,54 @@ same = (a, b) ->
 
   true
 
---- Interface for types.
+--- Base class for types.
 -- @type Type
 class Type
-  new: =>
-
   --- pretty-print a value of this type.
   -- @function pp
   -- @tparam any value
   -- @treturn string
 
+  --- create a `SigStream` of this type.
+  -- @tparam ?any init initial value
+  -- @treturn SigStream
+  mk_sig: (init) =>
+    result.SigStream @, init
+
+  --- create a `EvtStream` of this type.
+  -- @treturn EvtStream
+  mk_evt: =>
+    result.EvtStream @
+
+  --- create a `Constant` of this type.
+  -- @tparam any val value
+  -- @treturn Constant
+  mk_const: (val) =>
+    result.Constant @, val
+
 --- Primitive type.
 --
--- Implements the `Type` interface.
+-- Extends `Type`.
 --
 -- @type Primitive
-class Primitive
+class Primitive extends Type
   pp: (value) => tostring value
 
-  __eq: (other) => @type == other.type
-  __tostring: => @type
-
-  --- shorthand for number type.
-  -- @tfield Primitive num
-  @num: @ 'num'
-
-  --- shorthand for string type.
-  -- @tfield Primitive str
-  @str: @ 'str'
-
-  --- shorthand for symbol type.
-  -- @tfield Primitive sym
-  @sym: @ 'sym'
-
-  --- shorthand for boolean type.
-  -- @tfield Primitive bool
-  @bool: @ 'bool'
-
-  --- shorthand for bang type.
-  -- @tfield Primitive bang
-  @bang: @ 'bang'
-
-  --- shorthand for `Scope` type.
-  -- @tfield Primitive scope
-  @scope: @ 'scope'
-
-  --- shorthand for `Op` type.
-  -- @tfield Primitive op
-  @op: @ 'opdef'
-
-  --- shorthand for `FnDef` type.
-  -- @tfield Primitive fn
-  @fn: @ 'fndef'
-
-  --- shorthand for `Builtin` type.
-  -- @tfield Primitive builtin
-  @builtin: @ 'builtin'
+  __eq: (other) => @name == other.name
+  __tostring: => @name
 
   --- instantiate a Primitive type.
   -- @classmethod
-  -- @tparam string type the typename
-  new: (@type) =>
+  -- @tparam string name the typename
+  new: (@name) =>
+    assert (type @name) == 'string', "Typename has to be a string: '#{@name}'"
 
 --- Struct/Hashmap type.
 --
--- Implements the `Type` interface.
+-- Extends `Type`.
 --
 -- @type Struct
-class Struct
+class Struct extends Type
   pp: (value) =>
     inner = table.concat ["#{k}: #{@types[k]\pp v}" for k, v in opairs value], ', '
     "{#{inner}}"
@@ -111,10 +92,10 @@ class Struct
 
 --- Array type.
 --
--- Implements the `Type` interface.
+-- Extends `Type`.
 --
 -- @type Array
-class Array
+class Array extends Type
   pp: (value) =>
     inner = table.concat [@type\pp v for v in *value], ' '
     "[#{inner}]"
@@ -128,7 +109,17 @@ class Array
   -- @tparam Type type
   new: (@size, @type) =>
 
+--- Magic table containing all `Primitive` types.
+--
+-- When indexed with a string returns a (cached) instance of that type.
+--
+-- @table T
+T = setmetatable {}, __index: (key) =>
+  with type = Primitive key
+    rawset @, key, type
+
 {
+  :T
   :Primitive
   :Array
   :Struct
diff --git a/docs/gen/index b/docs/gen/index
index a2fe486..55dd1df 100755
--- a/docs/gen/index
+++ b/docs/gen/index
@@ -1,4 +1,5 @@
 #!/usr/bin/env moon
+require 'alv'
 import render, layout, autoref from require 'docs.gen.layout'
 import section, h1, h2, p, ul, li, a, code from require 'docs.gen.dom'
 import opairs from require 'alv.util'
@@ -43,6 +44,6 @@ spit OUT, layout
       p "These definitions are automatically loaded into the global Scope of
         every alive session."
       ul for key, val in opairs (require 'alv.builtin').values
-        li render key, val.value
+        li render key, val.result
     }
   }
diff --git a/docs/gen/layout.moon b/docs/gen/layout.moon
index 60ee80d..f695963 100644
--- a/docs/gen/layout.moon
+++ b/docs/gen/layout.moon
@@ -21,13 +21,13 @@ render = (name, result, prefix=nil, index=false) ->
   import div, label, code, ul, li, i, a, pre from dom
 
   id = if prefix then "#{prefix}/#{name}" else name
-  type = i tostring result.type
+  typestr = i tostring result.type
   assert result.meta, "#{id} doesn't have any metadata!"
   summary = assert result.meta.summary, "#{id} doesn't have a summary!"
 
   if index
     div {
-      label (a (code name), href: "##{id}"), ' (', type, '): &ensp;&ndash;&ensp;'
+      label (a (code name), href: "##{id}"), ' (', typestr, '): &ensp;&ndash;&ensp;'
       summary
     }
   else
@@ -41,7 +41,7 @@ render = (name, result, prefix=nil, index=false) ->
     content.class = 'nest'
     div {
       :id, class: 'def'
-      label (a (code name), href: "##{id}"), ' (', type, '): &ensp;&ndash;&ensp;'
+      label (a (code name), href: "##{id}"), ' (', typestr, '): &ensp;&ndash;&ensp;'
       summary
       div content
     }
diff --git a/spec/input_spec.moon b/spec/input_spec.moon
index 8a8defe..8dbd726 100644
--- a/spec/input_spec.moon
+++ b/spec/input_spec.moon
@@ -1,130 +1,160 @@
 import do_setup, do_teardown from require 'spec.test_setup'
-import Input, Primitive, Result, SigStream, EvtStream, IOStream
-  from require 'alv.base'
+import Input, T, Result, IOStream from require 'alv.base'
 
 setup do_setup
 teardown do_teardown
 
-my_io = Primitive 'my-io'
-
 class MyIO extends IOStream
-  new: => super my_io
+  new: => super T.my_io
   dirty: => @is_dirty
 
-basic_tests = (stream, input) ->
+basic_tests = (result, input) ->
   it 'gives access to the Result', ->
-    assert.is.equal stream, input.stream
+    assert.is.equal result, input.result
 
   it 'forwards :unwrap', ->
-    assert.is.same stream\unwrap!, input\unwrap!
-    assert.is.same stream\unwrap!, input!
+    assert.is.same result\unwrap!, input\unwrap!
+    assert.is.same result\unwrap!, input!
 
   it 'gives access to the type string', ->
-    assert.is.equal stream.type, input\type!
+    assert.is.equal result.type, input\type!
 
   it 'gives access to the metatype string', ->
-    assert.is.equal stream.metatype, input\metatype!
+    assert.is.equal result.metatype, input\metatype!
 
 describe 'Input.cold', ->
-  stream = SigStream.num 1
-  input = Input.cold stream
+  result = T.num\mk_sig 1
+  input = Input.cold result
 
-  basic_tests stream, input
+  basic_tests result, input
 
   it 'is never dirty', ->
     assert.is.false input\dirty!
-    stream\set 2
+    result\set 2
     assert.is.false input\dirty!
 
     input\setup nil
     assert.is.false input\dirty!
     input\finish_setup!
 
-    new_input = Input.cold SigStream.num 3
+    new_input = Input.cold T.num\mk_sig 3
     new_input\setup input
     assert.is.false new_input\dirty!
-    new_input.stream\set 4
+    new_input.result\set 4
     assert.is.false new_input\dirty!
     input\finish_setup!
 
 describe 'Input.hot', ->
+  describe 'with Constant', ->
+    result = T.num\mk_const 1
+    input = Input.hot result
+
+    basic_tests result, input
+
+    describe 'at evaltime', ->
+      it 'is dirty when new', ->
+        assert.is.false result\dirty!
+
+        newinput = Input.hot result
+        newinput\setup nil
+        assert.is.true newinput\dirty!
+        newinput\finish_setup!
+
+      it 'is dirty when different', ->
+        newval = T.num\mk_const 2
+
+        assert.is.false newval\dirty!
+        newinput = Input.hot newval
+        newinput\setup input
+        assert.is.true newinput\dirty!
+        newinput\finish_setup!
+
+      it 'is not dirty when equal', ->
+        newval = T.num\mk_const 1
+
+        assert.is.false newval\dirty!
+        newinput = Input.hot newval
+        newinput\setup input
+        assert.is.false newinput\dirty!
+        newinput\finish_setup!
+
   describe 'with EvtStream', ->
-    stream = EvtStream Primitive 'num'
-    input = Input.hot stream
+    result = T.num\mk_evt!
+    input = Input.hot result
 
-    basic_tests stream, input
+    basic_tests result, input
 
     it 'is marked for lifting', ->
       assert.is.nil input.io
 
     it 'is dirty when the EvtStream is dirty', ->
       assert.is.false input\dirty!
-      assert.is.false stream\dirty!
+      assert.is.false result\dirty!
 
       input\setup nil
       assert.is.false input\dirty!
       input\finish_setup!
 
       COPILOT\next_tick!
-      stream\add 1
+      result\add 1
 
       assert.is.true input\dirty!
-      assert.is.true stream\dirty!
+      assert.is.true result\dirty!
 
       input\setup nil
       assert.is.true input\dirty!
       input\finish_setup!
 
       assert.is.true input\dirty!
-      assert.is.true stream\dirty!
+      assert.is.true result\dirty!
 
   describe 'with IOStream', ->
-    stream = MyIO!
-    input = Input.hot stream
+    result = MyIO!
+    input = Input.hot result
 
-    basic_tests stream, input
+    basic_tests result, input
 
     it 'is marked for lifting', ->
       assert.is.true input.io
 
     it 'is dirty when the IOStream is dirty', ->
-      stream.is_dirty = false
+      result.is_dirty = false
 
       assert.is.false input\dirty!
-      assert.is.false stream\dirty!
+      assert.is.false result\dirty!
 
       input\setup nil
       assert.is.false input\dirty!
       input\finish_setup!
 
       COPILOT\next_tick!
-      stream.is_dirty = true
+      result.is_dirty = true
 
       assert.is.true input\dirty!
-      assert.is.true stream\dirty!
+      assert.is.true result\dirty!
 
       input\setup nil
       assert.is.true input\dirty!
       input\finish_setup!
 
       assert.is.true input\dirty!
-      assert.is.true stream\dirty!
+      assert.is.true result\dirty!
 
   describe 'with SigStream', ->
-    stream = SigStream.num 1
+    result = T.num\mk_sig 1
     local input
 
     describe 'at evaltime', ->
       it 'is dirty when new', ->
-        assert.is.false stream\dirty!
+        assert.is.false result\dirty!
 
-        input = Input.hot stream
+        input = Input.hot result
         input\setup nil
         assert.is.true input\dirty!
         input\finish_setup!
 
       it 'is dirty when different', ->
-        newval = SigStream.num 2
+        newval = T.num\mk_sig 2
 
         assert.is.false newval\dirty!
         newinput = Input.hot newval
@@ -133,7 +163,7 @@ describe 'Input.hot', ->
         newinput\finish_setup!
 
       it 'is not dirty when equal', ->
-        newval = SigStream.num!
+        newval = T.num\mk_sig!
         newval\set 1
 
         assert.is.true newval\dirty!
@@ -143,11 +173,11 @@ describe 'Input.hot', ->
         newinput\finish_setup!
 
     describe 'at runtime', ->
-      it 'is dirty when the stream is dirty', ->
-        stream\set 3
-        assert.is.true stream\dirty!
+      it 'is dirty when the result is dirty', ->
+        result\set 3
+        assert.is.true result\dirty!
         assert.is.true input\dirty!
 
         COPILOT\next_tick!
-        assert.is.false stream\dirty!
+        assert.is.false result\dirty!
         assert.is.false input\dirty!
diff --git a/spec/match_spec.moon b/spec/match_spec.moon
index 1e2ce61..afaef56 100644
--- a/spec/match_spec.moon
+++ b/spec/match_spec.moon
@@ -1,13 +1,13 @@
 import val, evt from require 'alv.base.match'
-import RTNode, Primitive, SigStream, EvtStream, Error from require 'alv'
+import RTNode, T, Error from require 'alv'
 
 mk_val = (type, const) ->
-  result = SigStream Primitive type
+  result = T[type]\mk_sig!
   with RTNode :result
     .side_inputs = { 'fake' } unless const
 
 mk_evt = (type, const) ->
-  result = EvtStream Primitive type
+  result = T[type]\mk_evt!
   with RTNode :result
     .side_inputs = { 'fake' } unless const
 
diff --git a/spec/result/const_spec.moon b/spec/result/const_spec.moon
index dfcdafa..a6ab43e 100644
--- a/spec/result/const_spec.moon
+++ b/spec/result/const_spec.moon
@@ -1,5 +1,5 @@
 import do_setup from require 'spec.test_setup'
-import Constant, RTNode, Scope, SimpleRegistry, Primitive from require 'alv'
+import Constant, RTNode, Scope, SimpleRegistry, T from require 'alv'
 import Op, Builtin from require 'alv.base'
 
 class TestOp extends Op
@@ -11,15 +11,20 @@ class TestBuiltin extends Builtin
 setup do_setup
 
 describe 'Constant', ->
+  it 'requires a value', ->
+    assert.has.error -> Constant.num!
+    assert.has.error -> Constant T.num
+    assert.has.no.error -> Constant T.bool, false
+
   describe '.wrap', ->
     it 'wraps numbers', ->
       got = Constant.wrap 3
-      assert.is.equal Primitive.num, got.type
+      assert.is.equal T.num, got.type
       assert.is.equal 3, got.value
 
     it 'wraps strings', ->
       got = Constant.wrap "im a happy string"
-      assert.is.equal Primitive.str, got.type
+      assert.is.equal T.str, got.type
       assert.is.equal "im a happy string", got.value
 
     it 'wraps Constants', ->
@@ -31,27 +36,27 @@ describe 'Constant', ->
     it 'wraps Opdefs', ->
       got = Constant.wrap TestOp
 
-      assert.is.equal Primitive.op, got.type
+      assert.is.equal T.opdef, got.type
       assert.is.equal TestOp, got.value
 
     it 'wraps Bultins', ->
       got = Constant.wrap TestBuiltin
 
-      assert.is.equal Primitive.builtin, got.type
+      assert.is.equal T.builtin, got.type
       assert.is.equal TestBuiltin, got.value
 
     it 'wraps Scopes', ->
       sub = Scope!
       got = Constant.wrap sub
 
-      assert.is.equal Primitive.scope, got.type
+      assert.is.equal T.scope, got.type
       assert.is.equal sub, got.value
 
     it 'wraps tables', ->
       pi = Constant.num 3.14
       got = Constant.wrap { :pi }
 
-      assert.is.equal Primitive.scope, got.type
+      assert.is.equal T.scope, got.type
       assert.is.equal pi, (got.value\get 'pi')\const!
 
   describe ':unwrap', ->
@@ -61,23 +66,23 @@ describe 'Constant', ->
       assert.is.equal 'hi', (Constant.sym 'hi')\unwrap!
 
     test 'can assert the type', ->
-      assert.is.equal 3.14, (Constant.num 3.14)\unwrap Primitive.num
-      assert.is.equal 'hi', (Constant.str 'hi')\unwrap Primitive.str
-      assert.is.equal 'hi', (Constant.sym 'hi')\unwrap Primitive.sym
-      assert.has_error -> (Constant.num 3.14)\unwrap Primitive.sym
-      assert.has_error -> (Constant.str 'hi')\unwrap Primitive.num
-      assert.has_error -> (Constant.sym 'hi')\unwrap Primitive.str
+      assert.is.equal 3.14, (Constant.num 3.14)\unwrap T.num
+      assert.is.equal 'hi', (Constant.str 'hi')\unwrap T.str
+      assert.is.equal 'hi', (Constant.sym 'hi')\unwrap T.sym
+      assert.has_error -> (Constant.num 3.14)\unwrap T.sym
+      assert.has_error -> (Constant.str 'hi')\unwrap T.num
+      assert.has_error -> (Constant.sym 'hi')\unwrap T.str
 
     test 'has __call shorthand', ->
       assert.is.equal 3.14, (Constant.num 3.14)!
       assert.is.equal 'hi', (Constant.str 'hi')!
       assert.is.equal 'hi', (Constant.sym 'hi')!
-      assert.is.equal 3.14, (Constant.num 3.14) Primitive.num
-      assert.is.equal 'hi', (Constant.str 'hi') Primitive.str
-      assert.is.equal 'hi', (Constant.sym 'hi') Primitive.sym
-      assert.has_error -> (Constant.num 3.14) Primitive.sym
-      assert.has_error -> (Constant.str 'hi') Primitive.num
-      assert.has_error -> (Constant.sym 'hi') Primitive.str
+      assert.is.equal 3.14, (Constant.num 3.14) T.num
+      assert.is.equal 'hi', (Constant.str 'hi') T.str
+      assert.is.equal 'hi', (Constant.sym 'hi') T.sym
+      assert.has_error -> (Constant.num 3.14) T.sym
+      assert.has_error -> (Constant.str 'hi') T.num
+      assert.has_error -> (Constant.sym 'hi') T.str
 
   describe 'overrides __eq', ->
     it 'compares the type', ->
@@ -134,7 +139,7 @@ describe 'Constant', ->
     it 'is equal to the original', ->
       a = Constant.num 2
       b = Constant.str 'asdf'
-      c = Constant (Primitive 'weird'), {}, '(raw)'
+      c = Constant T.weird, {}, '(raw)'
 
       aa, bb, cc = a\fork!, b\fork!, c\fork!
       assert.is.equal a, aa
diff --git a/spec/result/sig_spec.moon b/spec/result/sig_spec.moon
index 93a9eb4..4d04b9c 100644
--- a/spec/result/sig_spec.moon
+++ b/spec/result/sig_spec.moon
@@ -1,5 +1,5 @@
 import do_setup from require 'spec.test_setup'
-import SigStream, RTNode, Scope, SimpleRegistry, Primitive from require 'alv'
+import SigStream, RTNode, Scope, SimpleRegistry, T from require 'alv'
 import Op, Builtin from require 'alv.base'
 
 class TestOp extends Op
@@ -13,55 +13,55 @@ setup do_setup
 describe 'SigStream', ->
   describe ':unwrap', ->
     it 'returns the raw value!', ->
-      assert.is.equal 3.14, (SigStream.num 3.14)\unwrap!
-      assert.is.equal 'hi', (SigStream.str 'hi')\unwrap!
-      assert.is.equal 'hi', (SigStream.sym 'hi')\unwrap!
+      assert.is.equal 3.14, (SigStream T.num, 3.14)\unwrap!
+      assert.is.equal 'hi', (SigStream T.str, 'hi')\unwrap!
+      assert.is.equal 'hi', (SigStream T.sym, 'hi')\unwrap!
 
     test 'can assert the type', ->
-      assert.is.equal 3.14, (SigStream.num 3.14)\unwrap Primitive 'num'
-      assert.is.equal 'hi', (SigStream.str 'hi')\unwrap Primitive 'str'
-      assert.is.equal 'hi', (SigStream.sym 'hi')\unwrap Primitive 'sym'
-      assert.has_error -> (SigStream.num 3.14)\unwrap Primitive 'sym'
-      assert.has_error -> (SigStream.str 'hi')\unwrap Primitive 'num'
-      assert.has_error -> (SigStream.sym 'hi')\unwrap Primitive 'str'
+      assert.is.equal 3.14, (SigStream T.num, 3.14)\unwrap T.num
+      assert.is.equal 'hi', (SigStream T.str, 'hi')\unwrap T.str
+      assert.is.equal 'hi', (SigStream T.sym, 'hi')\unwrap T.sym
+      assert.has_error -> (SigStream T.num, 3.14)\unwrap T.sym
+      assert.has_error -> (SigStream T.str, 'hi')\unwrap T.num
+      assert.has_error -> (SigStream T.sym, 'hi')\unwrap T.str
 
     test 'has __call shorthand', ->
-      assert.is.equal 3.14, (SigStream.num 3.14)!
-      assert.is.equal 'hi', (SigStream.str 'hi')!
-      assert.is.equal 'hi', (SigStream.sym 'hi')!
-      assert.is.equal 3.14, (SigStream.num 3.14) Primitive 'num'
-      assert.is.equal 'hi', (SigStream.str 'hi') Primitive 'str'
-      assert.is.equal 'hi', (SigStream.sym 'hi') Primitive 'sym'
-      assert.has_error -> (SigStream.num 3.14) Primitive 'sym'
-      assert.has_error -> (SigStream.str 'hi') Primitive 'num'
-      assert.has_error -> (SigStream.sym 'hi') Primitive 'str'
+      assert.is.equal 3.14, (SigStream T.num, 3.14)!
+      assert.is.equal 'hi', (SigStream T.str, 'hi')!
+      assert.is.equal 'hi', (SigStream T.sym, 'hi')!
+      assert.is.equal 3.14, (SigStream T.num, 3.14) T.num
+      assert.is.equal 'hi', (SigStream T.str, 'hi') T.str
+      assert.is.equal 'hi', (SigStream T.sym, 'hi') T.sym
+      assert.has_error -> (SigStream T.num, 3.14) T.sym
+      assert.has_error -> (SigStream T.str, 'hi') T.num
+      assert.has_error -> (SigStream T.sym, 'hi') T.str
 
   describe 'overrides __eq', ->
     it 'compares the type', ->
-      val = SigStream.num 3
-      assert.is.equal (SigStream.num 3), val
-      assert.not.equal (SigStream.str '3'), val
+      val = SigStream T.num, 3
+      assert.is.equal (SigStream T.num, 3), val
+      assert.not.equal (SigStream T.str, '3'), val
 
-      val = SigStream.str 'hello'
-      assert.is.equal (SigStream.str 'hello'), val
-      assert.not.equal (SigStream.sym 'hello'), val
+      val = SigStream T.str, 'hello'
+      assert.is.equal (SigStream T.str, 'hello'), val
+      assert.not.equal (SigStream T.sym, 'hello'), val
 
     it 'compares the value', ->
-      val = SigStream.num 3
-      assert.is.equal (SigStream.num 3), val
-      assert.not.equal (SigStream.num 4), val
+      val = SigStream T.num, 3
+      assert.is.equal (SigStream T.num, 3), val
+      assert.not.equal (SigStream T.num, 4), val
 
   describe ':set', ->
     it 'sets the value', ->
-      val = SigStream.num 3
-      assert.is.equal (SigStream.num 3), val
+      val = SigStream T.num, 3
+      assert.is.equal (SigStream T.num, 3), val
 
       val\set 4
-      assert.is.equal (SigStream.num 4), val
-      assert.not.equal (SigStream.num 3), val
+      assert.is.equal (SigStream T.num, 4), val
+      assert.not.equal (SigStream T.num, 3), val
 
     it 'marks the value dirty', ->
-      val = SigStream.num 3
+      val = SigStream T.num, 3
       assert.is.false val\dirty!
 
       val\set 4
@@ -69,9 +69,9 @@ describe 'SigStream', ->
 
   describe ':fork', ->
     it 'is equal to the original', ->
-      a = SigStream.num 2
-      b = SigStream.str 'asdf'
-      c = with SigStream 'weird', {}, '(raw)'
+      a = SigStream T.num, 2
+      b = SigStream T.str, 'asdf'
+      c = with SigStream T.weird, {}, '(raw)'
         \set {}
 
       aa, bb, cc = a\fork!, b\fork!, c\fork!
@@ -86,8 +86,8 @@ describe 'SigStream', ->
       assert.is.equal c.raw, cc.raw
 
     it 'isolates the original from the fork', ->
-      a = SigStream.num 3
-      b = with SigStream 'weird', {}, '(raw)'
+      a = SigStream T.num, 3
+      b = with SigStream T.weird, {}, '(raw)'
         \set {}
 
       aa, bb = a\fork!, b\fork!
diff --git a/spec/rtnode_spec.moon b/spec/rtnode_spec.moon
index a6cd63d..5dfebf7 100644
--- a/spec/rtnode_spec.moon
+++ b/spec/rtnode_spec.moon
@@ -1,11 +1,8 @@
 import do_setup from require 'spec.test_setup'
 import RTNode, Scope, SimpleRegistry from require 'alv'
-import Primitive, Input, Op, Constant, SigStream, EvtStream, IOStream
-  from require 'alv.base'
+import T, Input, Op, Constant, IOStream from require 'alv.base'
 
 setup do_setup
-num = Primitive 'num'
-bang = Primitive 'bang'
 
 op_with_inputs = (inputs) ->
   with Op!
@@ -16,7 +13,7 @@ node_with_sideinput = (result, input) ->
     .side_inputs = { [result]: input }
 
 class DirtyIO extends IOStream
-  new: => super Primitive 'dirty-io'
+  new: => super T.dirty_io
   dirty: => true
 
 describe 'RTNode', ->
@@ -34,7 +31,7 @@ describe 'RTNode', ->
 
   it ':type gets type and assets value', ->
     node = RTNode result: Constant.num 2
-    assert.is.equal num, node\type!
+    assert.is.equal T.num, node\type!
 
     node = RTNode!
     assert.has.error -> node\type!
@@ -52,7 +49,7 @@ describe 'RTNode', ->
     assert.has.error (-> impure\const 'test'), 'test'
 
   it ':make_ref', ->
-    result = SigStream.num 2
+    result = T.num\mk_sig 2
     input = Input.hot result
     op = op_with_inputs { input }
     thick = RTNode :result, :op, children: { RTNode!, RTNode! }
@@ -65,10 +62,10 @@ describe 'RTNode', ->
     assert.is.nil ref.op
 
   it 'lifts up inputs from op', ->
-    event = EvtStream bang
+    event = T.bang\mk_evt!
     event_input = Input.hot event
 
-    value = SigStream num, 4
+    value = T.num\mk_sig 4
     value_input = Input.hot value
 
     op = op_with_inputs { event_input, value_input }
@@ -79,10 +76,10 @@ describe 'RTNode', ->
                    node.side_inputs
 
   it 'does not lift up op inputs that are also child values', ->
-    event = EvtStream bang
+    event = T.bang\mk_evt!
     event_input = Input.hot event
 
-    result = SigStream num, 4
+    result = T.num\mk_sig 4
     value_input = Input.hot result
 
     op = op_with_inputs { event_input, value_input }
@@ -91,12 +88,12 @@ describe 'RTNode', ->
     assert.is.same { [event]: event_input }, node.side_inputs
 
   it 'lifts up side_inputs from children', ->
-    event_value = EvtStream bang
+    event_value = T.bang\mk_evt!
     event_input = Input.hot event_value
     event = RTNode op: op_with_inputs { event_input }
     assert.is.same { [event_value]: event_input }, event.side_inputs
 
-    value_value = SigStream num, 4
+    value_value = T.num\mk_sig 4
     value_input = Input.hot value_value
     value = RTNode op: op_with_inputs { value_input }
     assert.is.same { [value_value]: value_input }, value.side_inputs
@@ -109,11 +106,11 @@ describe 'RTNode', ->
     local a_value, a_child, a_input
     local b_value, b_child, b_input
     before_each ->
-      a_value = EvtStream num
+      a_value = T.num\mk_evt!
       a_input = Input.hot a_value
       a_child = node_with_sideinput a_value, a_input
 
-      b_value = EvtStream num
+      b_value = T.num\mk_evt!
       b_input = Input.hot b_value
       b_child = node_with_sideinput b_value, b_input
 
diff --git a/spec/scope_spec.moon b/spec/scope_spec.moon
index 7278b9e..637b5f5 100644
--- a/spec/scope_spec.moon
+++ b/spec/scope_spec.moon
@@ -1,4 +1,4 @@
-import Scope, Primitive, Constant, RTNode from require 'alv'
+import Scope, T, Constant, RTNode from require 'alv'
 import Op from require 'alv.base'
 import Logger from require 'alv.logger'
 Logger\init 'silent'
@@ -8,11 +8,6 @@ class TestOp extends Op
 
 wrap_res = (result) -> RTNode :result
 
-num = Primitive 'num'
-str = Primitive 'str'
-opdef = Primitive 'opdef'
-scope_t = Primitive 'scope'
-
 describe 'Scope', ->
   describe 'constifies', ->
     scope = Scope!
@@ -38,21 +33,21 @@ describe 'Scope', ->
       scope\set_raw 'test', TestOp
 
       got = (scope\get 'test')\const!
-      assert.is.equal TestOp, got opdef
+      assert.is.equal TestOp, got T.opdef
 
     test 'Scopes', ->
       sub = Scope!
       scope\set_raw 'sub', sub
 
       got = (scope\get 'sub')\const!
-      assert.is.equal sub, got scope_t
+      assert.is.equal sub, got T.scope
 
     test 'tables', ->
       pi = Constant.num 3.14
       scope\set_raw 'math', { :pi }
 
       got = (scope\get 'math')\const!
-      assert.is.equal scope_t, got.type
+      assert.is.equal T.scope, got.type
       assert.is.equal Scope, got.value.__class
       assert.is.equal pi, (got.value\get 'pi')\const!
       assert.is.equal pi, (scope\get 'math/pi')\const!
@@ -68,18 +63,18 @@ describe 'Scope', ->
     }
 
     got = (scope\get 'num')\const!
-    assert.is.equal 3, got num
+    assert.is.equal 3, got T.num
 
     got = (scope\get 'str')\const!
-    assert.is.equal "im a happy string", got str
+    assert.is.equal "im a happy string", got T.str
 
     assert.is.equal pi, (scope\get 'pi')\const!
 
     got = (scope\get 'test')\const!
-    assert.is.equal TestOp, got opdef
+    assert.is.equal TestOp, got T.opdef
 
     got = (scope\get 'math')\const!
-    assert.is.equal scope_t, got.type
+    assert.is.equal T.scope, got.type
     assert.is.equal pi, (scope\get 'math/pi')\const!
 
   it 'gets from nested scopes', ->
@@ -116,13 +111,13 @@ describe 'Scope', ->
 
     it 'allows access', ->
       got = (scope\get 'inherited')\const!
-      assert.is.equal "inherited string", got str
+      assert.is.equal "inherited string", got T.str
 
     it 'can be shadowed', ->
       scope\set_raw 'hidden', "overwritten"
 
       got = (scope\get 'hidden')\const!
-      assert.is.equal "overwritten", got str
+      assert.is.equal "overwritten", got T.str
 
   describe 'dynamic inheritance', ->
     root = Scope!
diff --git a/spec/type_spec.moon b/spec/type_spec.moon
index 14d7894..d33fcb4 100644
--- a/spec/type_spec.moon
+++ b/spec/type_spec.moon
@@ -1,5 +1,5 @@
 require 'spec.test_setup'
-import Primitive, Array, Struct from require 'alv'
+import T, Primitive, Array, Struct from require 'alv'
 
 bool = Primitive 'bool'
 num = Primitive 'num'
@@ -43,3 +43,36 @@ describe 'Struct', ->
     assert.not.equal play, Struct { note: str }
     assert.not.equal play, Struct { note: str, dur: str }
     assert.not.equal play, Struct { note: str, dur: num, extra: num }
+
+describe 'T', ->
+  it 'provides shorthand for Primitives', ->
+    assert.is.equal num, T.num
+    assert.is.equal str, T.str
+    assert.is.equal (Primitive 'midi/evt'), T['midi/evt']
+
+for type in *{num, str, (Array 3, num)}
+  describe "#{type}", ->
+    describe ':mk_sig', ->
+      it 'can create value-less Streams', ->
+        stream = type\mk_sig!
+        assert.is.equal 'SigStream', stream.__class.__name
+        assert.is.equal type, stream.type
+        assert.is.nil stream!
+
+      it 'can take an initial value', ->
+        stream = type\mk_sig 4
+        assert.is.equal 'SigStream', stream.__class.__name
+        assert.is.equal type, stream.type
+        assert.is.equal 4, stream!
+
+    describe ':mk_const', ->
+      it 'takes a value', ->
+        stream = type\mk_const 4
+        assert.is.equal 'Constant', stream.__class.__name
+        assert.is.equal type, stream.type
+        assert.is.equal 4, stream!
+
+    describe ':mk_evt', ->
+      stream = type\mk_evt!
+      assert.is.equal 'EvtStream', stream.__class.__name
+      assert.is.equal type, stream.type