1 files changed, 69 insertions, 0 deletions
diff --git a/core/base.moon b/core/base.moon
new file mode 100644
index 0000000..1805bea
--- /dev/null
+++ b/core/base.moon
@@ -0,0 +1,69 @@
+class Op
+-- common
+  new: =>
+  -- (...) => @setup ...
+
+  get: => @value
+  getc: =>
+    L\warn "stream #{@} cast to constant"
+    @value
+
+-- Value interface
+  update: =>
+
+  destroy: =>
+
+-- static
+  __tostring: => "<op: #{@@__name}>"
+  __inherited: (cls) => cls.__base.__tostring = @__tostring
+
+  spawn: (Opdef, ...) ->
+    Opdef ...
+
+class Action
+-- common
+  new: (head, @tag, @registry) =>
+    @patch head
+
+  register: =>
+    @tag = @registry\register @, @tag
+
+-- AST interface
+  -- * eval args
+  -- * perform scope effects
+  -- * patch nested exprs
+  -- * return runtime-tree value
+  eval: (scope, tail) => error "not implemented"
+
+  -- free resources
+  destroy: =>
+
+  -- update this instance for :eavl() with new head
+  -- if :patch() returns false, this instance is :destroy'ed and recreated instead
+  -- must *not* return false when called after :new()
+  -- only considered if Action types match
+  patch: (head) =>
+    if head == @head
+      true
+
+    @head = head
+
+-- static
+  @get_or_create: (ActionType, head, tag, registry) ->
+    last = tag and registry\prev tag
+    compatible = last and
+                 (last.__class == ActionType) and
+                 (last\patch head) and
+                 last
+
+    if not compatible
+      last\destroy! if last
+      compatible = ActionType head, tag, registry
+
+    with compatible
+      \register!
+
+  __tostring: => "<action: #{@@__name}>"
+  __inherited: (cls) => cls.__base.__tostring = @__tostring
+
+:Op, :Action