remove IOStreams, support optional polling in Ops

10 files changed, 79 insertions, 138 deletions

diff --git a/alv/base/init.moon b/alv/base/init.moon
index 586a6bd..69979a5 100644
--- a/alv/base/init.moon
+++ b/alv/base/init.moon
@@ -16,7 +16,6 @@
 -- @see Constant
 -- @see SigStream
 -- @see EvtStream
--- @see IOStream
 -- @see type.T
 -- @see type.Primitive
 -- @see type.Array
@@ -30,7 +29,7 @@ import Builtin from require 'alv.base.builtin'
 import FnDef from require 'alv.base.fndef'
 import Input from require 'alv.base.input'
 import const, sig, evt from require 'alv.base.match'
-import Constant, SigStream, EvtStream, IOStream from require 'alv.result'
+import Constant, SigStream, EvtStream from require 'alv.result'
 import T, Primitive, Array, Struct from require 'alv.type'
 import RTNode from require 'alv.rtnode'
 import Error from require 'alv.error'
@@ -45,7 +44,7 @@ import Error from require 'alv.error'
   -- redundant exports, to keep anything an extension might need in one import
 
   -- Results
-  :Constant, :SigStream, :EvtStream, :IOStream
+  :Constant, :SigStream, :EvtStream
 
   -- Types
   :T, :Primitive, :Array, :Struct
diff --git a/alv/base/input.moon b/alv/base/input.moon
index f29bd10..87e00de 100644
--- a/alv/base/input.moon
+++ b/alv/base/input.moon
@@ -2,7 +2,7 @@
 -- Update scheduling policy for `Op` arguments.
 --
 -- @classmod Input
-import Constant, SigStream, EvtStream, IOStream from require 'alv.result'
+import Constant, SigStream, EvtStream from require 'alv.result'
 import RTNode from require 'alv.rtnode'
 
 inherits = (klass, frm) ->
@@ -112,9 +112,8 @@ class Input
   -- Behaviour depends on what kind of `Result` `value` is:
   --
   -- - `Constant`: treated like `cold`.
-  -- - `SigStream`: Marked dirty only if old and new `SigStream` differ.
-  -- - `EvtStream` and `IOStream`: Marked dirty only if the current
-  --   `EvtStream` is dirty.
+  -- - `SigStream`: Marked dirty only if old and new `result` differ.
+  -- - `EvtStream`: Marked dirty only if the current `result` is dirty.
   --
   -- This is the most common `Input` strategy.
   --
@@ -152,7 +151,6 @@ mapping = {
   [Constant]: ValueInput
   [SigStream]: ValueInput
   [EvtStream]: Input
-  [IOStream]: IOInput
 }
 
 {
diff --git a/alv/base/match.moon b/alv/base/match.moon
index 4653107..f5fa99c 100644
--- a/alv/base/match.moon
+++ b/alv/base/match.moon
@@ -295,7 +295,7 @@ sig = setmetatable {}, {
   __call: (...) => Type '~', ...
 }
 
---- `Type` shorthands for matching `EvtStream` and `IOStream`s.
+--- `Type` shorthands for matching `EvtStream`s.
 --
 -- Call or index with a string to obtain an `Type` instance.
 -- Call to obtain a wildcard pattern.
diff --git a/alv/base/op.moon b/alv/base/op.moon
index f20518d..bb48b09 100644
--- a/alv/base/op.moon
+++ b/alv/base/op.moon
@@ -112,6 +112,18 @@ class Op
     else
       {}
 
+  --- poll for external changes (optional).
+  --
+  -- If implemented, this method will be called at a high frequency and should
+  -- return `true` whenever processing is required due to an external event or
+  -- condition. After polling all such IO Ops a new tick will be executed if any
+  -- returned true. The implementation of `poll` is responsible for triggering
+  -- the `tick` method by writing to an internally allocated `Result` that has
+  -- been inserted into `inputs`.
+  --
+  -- @function poll
+  -- @treturn ?boolean dirty whether processing is required
+
 --- implementation utilities.
 --
 -- super-methods and utilities for use by implementations.
diff --git a/alv/init.moon b/alv/init.moon
index 7ff3e99..3de3c9b 100644
--- a/alv/init.moon
+++ b/alv/init.moon
@@ -15,7 +15,7 @@ version = require 'alv.version'
 import Logger from require 'alv.logger'
 
 import T, Primitive, Struct, Array from require 'alv.type'
-import Constant, SigStream, EvtStream, IOStream from require 'alv.result'
+import Constant, SigStream, EvtStream from require 'alv.result'
 import RTNode from require 'alv.rtnode'
 import Scope from require 'alv.scope'
 import Error from require 'alv.error'
@@ -37,7 +37,6 @@ cycle\resolve!
 -- @tfield Constant Constant
 -- @tfield SigStream SigStream
 -- @tfield EvtStream EvtStream
--- @tfield IOStream IOStream
 -- @tfield type.T T
 -- @tfield type.Primitive Primitive
 -- @tfield type.Array Array
@@ -55,7 +54,7 @@ cycle\resolve!
 {
   :version
 
-  :Constant, :SigStream, :EvtStream, :IOStream
+  :Constant, :SigStream, :EvtStream
   :Cell, :RootCell
   :RTNode, :Scope, :Error
 
diff --git a/alv/result/base.moon b/alv/result/base.moon
index 734d614..a9a668d 100644
--- a/alv/result/base.moon
+++ b/alv/result/base.moon
@@ -1,7 +1,7 @@
 ----
 -- base Result interface.
 --
--- implemented by `Constant`, `SigStream`, `EvtStream`, and `IOStream`.
+-- implemented by `Constant`, `SigStream`, and `EvtStream`.
 --
 -- @classmod Result
 import Type from require 'alv.type'
@@ -11,7 +11,7 @@ class Result
 --- Result interface.
 --
 -- Methods that have to be implemented by `Result` implementations
--- (`SigStream`, `EvtStream`, `IOStream`).
+-- (`Constant`, `SigStream`, `EvtStream`).
 --
 -- @section interface
 
@@ -38,8 +38,7 @@ class Result
 
   --- the metatype string for this Result.
   --
-  -- one of `=` (`Constant`), `~` (`SigStream`),
-  -- `!` (`EvtStream` and `IOStream`).
+  -- one of `=` (`Constant`), `~` (`SigStream`), `!` (`EvtStream`).
   --
   -- @tfield string metatype
 
diff --git a/alv/result/init.moon b/alv/result/init.moon
index 200e4e1..8e5c64f 100644
--- a/alv/result/init.moon
+++ b/alv/result/init.moon
@@ -5,17 +5,14 @@
 -- @see Constant
 -- @see SigStream
 -- @see EvtStream
--- @see IOStream
 --
 -- @module result
 import Constant from require 'alv.result.const'
 import SigStream from require 'alv.result.sig'
 import EvtStream from require 'alv.result.evt'
-import IOStream from require 'alv.result.io'
 
 {
   :Constant
   :SigStream
   :EvtStream
-  :IOStream
 }
diff --git a/alv/result/io.moon b/alv/result/io.moon
deleted file mode 100644
index f68f672..0000000
--- a/alv/result/io.moon
+++ /dev/null
@@ -1,55 +0,0 @@
-----
--- Stream of external side-effects.
---
--- Unlike other `Stream`s, this is not updated/set by an `Op` instace, but is
--- continuously polled for changes by the runtime and may mark itself as
--- *dirty* at any point in time. All runtime execution happens due to IOStream
--- updates, which ripple through the `RTNode` tree.
---
--- @classmod IOStream
-import EvtStream from require 'alv.result.evt'
-
-class IOStream extends EvtStream
---- IOStream interface.
---
--- methods that have to be implemented by `IOStream` implementations.
--- @section interface
-
-  --- construct a new IOStream.
-  --
-  -- Must prepare the instance for `dirty` to be called.
-  -- The super-constructor should be called to set `Result.type`.
-  --
-  -- @classmethod
-  -- @tparam type.Type type the type of this stream.
-  new: (type) => super type
-
-  --- create a mutable copy of this stream.
-  --
-  -- Used to wrap insulate eval-cycles from each other.
-  --
-  -- @treturn IOStream
-  fork: => @
-
-  --- poll for changes.
-  --
-  -- Called every frame by the main event loop to update internal state.
-  poll: =>
-
-  --- check whether this adapter requires processing.
-  --
-  -- Must return a boolean indicating whether `Op`s that refer to this instance
-  -- via `Input.hot` should be notified (via `Op:tick`). May be called multiple
-  -- times. May be called before `poll` on the first frame after construction.
-  --
-  -- If this is not overriden, the `EvtStream` interface can be used, see
-  -- `EvtStream.add`, `EvtStream.unwrap`, and `EvtStream.dirty`.
-  --
-  -- @function dirty
-  -- @treturn bool whether processing is required
-
-  __inherited: (cls) => cls.__base.__tostring or= @__tostring
-
-{
-  :IOStream
-}
diff --git a/alv/rtnode.moon b/alv/rtnode.moon
index 98c230e..28b1d77 100644
--- a/alv/rtnode.moon
+++ b/alv/rtnode.moon
@@ -5,7 +5,6 @@
 -- between `Op`s.
 --
 -- @classmod RTNode
-
 import Error from require 'alv.error'
 
 class RTNode
@@ -35,29 +34,38 @@ class RTNode
     @result.metatype
 
   --- create a copy of this result with result-copy semantics.
-  -- the copy has the same @result and @side_inputs, but will not update
-  -- anything on \tick.
+  --
+  -- the copy has the same @result and @side_inputs, but will not (doubly)update
+  -- anything on `tick` or `poll`.
   make_ref: =>
     RTNode result: @result, side_inputs: @side_inputs
 
-  --- poll all IOStream instances that are effecting this (sub)tree.
+  --- poll all IO Ops effecting this (sub)tree for changes.
+  --
   -- should be called once per frame on the root, right before tick.
+  --
+  -- @treturn ?boolean whether any IO Op marked itself dirty.
   poll_io: =>
-    for result, input in pairs @side_inputs
-      result\poll! if input.mode == 'io'
+    dirty = false
+
+    for op in *@io_ops
+      dirty or= op\poll!
+
+    dirty
 
   --- 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 result, input in pairs @side_inputs
-      if input\dirty!
-        any_dirty = true
-        break
+    if #@io_ops == 0
+      any_dirty = false
+      for result, input in pairs @side_inputs
+        if input\dirty!
+          any_dirty = true
+          break
 
-    -- early-out if no Inputs are dirty in this whole subtree
-    return unless any_dirty
+      -- early-out if no Inputs are dirty in this whole subtree
+      return unless any_dirty
 
     for child in *@children
       child\tick!
@@ -81,17 +89,17 @@ class RTNode
     buf ..= ">"
     buf
 
-  --- the `Result` result
-  --
+  --- the `Result` result.
   -- @tfield ?Result result
 
-  --- an Op
-  --
+  --- an Op.
   -- @tfield ?Op op
 
-  --- list of child `RTNode`s from subexpressions
-  --
-  -- @tfield {}|{RTNode,...} children
+  --- list of child `RTNode`s from subexpressions.
+  -- @tfield {RTNode,...} children
+
+  --- cached list of all IO Ops inside this RTNode and children.
+  -- @tfield {Op,...} io_ops
 
   --- cached mapping of all `Result`/`Input` pairs affecting this RTNode.
   --
@@ -110,28 +118,48 @@ class RTNode
     @result = params.result
     @op = params.op
     @children = params.children or {}
+    @io_ops = params.io_ops or {}
 
     if params.side_inputs
       @side_inputs = params.side_inputs
       return
 
-    @side_inputs, is_child = {}, {}
+    @side_inputs = {}
+    is_child = {}
+
     for child in *@children
+      -- collect child side_inputs
       for result, input in pairs child.side_inputs
         @side_inputs[result] = input
+
+      -- collect child io_ops
+      for op in *child.io_ops
+        table.insert @io_ops, op
+
       if child.result
         is_child[child.result] = true
 
     if @op
+      if @op.poll
+        table.insert @io_ops, @op
+
+      -- find inputs outside this tree
       for i in @op\all_inputs!
-        if i.mode == 'io' or (i.mode == 'hot' and not is_child[i.result])
+        if i.mode == 'hot' and not is_child[i.result]
           @side_inputs[i.result] = i
 
-    if @result
-      if next @side_inputs
-        assert @result.metatype != '=', "Const result #{@result} has side_inputs"
-      elseif @result.metatype == '~'
-        @result = @result.type\mk_const @result\unwrap!
+    -- "freeze" ~-streams if there are no IO Ops around
+    return unless @result and @result.metatype == '~'
+    return if #@io_ops > 0
+
+    all_const = true
+    for result, input in pairs @side_inputs
+      if result.metatype != '='
+        all_const = false
+        break
+    return unless all_const
+
+    @result = @result.type\mk_const @result\unwrap!
 
 {
   :RTNode
diff --git a/spec/input_spec.moon b/spec/input_spec.moon
index 9237fd8..04cf16e 100644
--- a/spec/input_spec.moon
+++ b/spec/input_spec.moon
@@ -1,13 +1,9 @@
 import do_setup, do_teardown from require 'spec.test_setup'
-import Input, T, Result, IOStream from require 'alv.base'
+import Input, T, Result from require 'alv.base'
 
 setup do_setup
 teardown do_teardown
 
-class MyIO extends IOStream
-  new: => super T.my_io
-  dirty: => @is_dirty
-
 basic_tests = (result, input) ->
   it 'gives access to the Result', ->
     assert.is.equal result, input.result
@@ -114,38 +110,6 @@ describe 'Input.hot', ->
       assert.is.true input\dirty!
       assert.is.true result\dirty!
 
-  describe 'with IOStream', ->
-    result = MyIO!
-    input = Input.hot result
-
-    basic_tests result, input
-
-    it 'is marked for lifting', ->
-      assert.is.equal 'io', input.mode
-
-    it 'is dirty when the IOStream is dirty', ->
-      result.is_dirty = false
-
-      assert.is.false input\dirty!
-      assert.is.false result\dirty!
-
-      input\setup nil
-      assert.is.false input\dirty!
-      input\finish_setup!
-
-      COPILOT\next_tick!
-      result.is_dirty = true
-
-      assert.is.true input\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 result\dirty!
-
   describe 'with SigStream', ->
     result = T.num\mk_sig 1
     local input