Calico interpreter returns signals

build.sbt

@@ -60,10 +60,10 @@ lazy val commonSettings = Seq(
   )
 )
 
-lazy val root = crossProject(JSPlatform, JVMPlatform)
+lazy val root = project
   .in(file("."))
   .settings(moduleName := "gooey")
-  .aggregate(core)
+  .aggregate(core.js, core.jvm, calico)
 
 lazy val core = crossProject(JSPlatform, JVMPlatform)
   .in(file("core"))

calico/src/main/scala/gooey/calico/Algebra.scala

@@ -1,7 +1,11 @@
 package gooey.calico
 
-import _root_.calico.html.io.{*, given}
+import _root_.calico.*
+import _root_.calico.html.io.{_, given}
+import _root_.calico.syntax.*
 import cats.effect.*
+import cats.syntax.all.*
+import fs2.concurrent.*
 import fs2.dom.*
 import gooey.component.*
 
@@ -10,18 +14,33 @@ object Algebra
       Textbox.Algebra,
       Checkbox.Algebra,
       Above.Algebra { self =>
-  type UI[A] = Resource[IO, HtmlElement[IO]]
+
+  final case class Component[A](element: HtmlElement[IO], output: Signal[IO, A])
+
+  type UI[A] = Resource[IO, Component[A]]
   def checkbox(c: Checkbox): UI[Boolean] = {
     val Checkbox(label, default) = c
-    div(p("checkbox placeholder for $label"))
+    val element = div(p("checkbox placeholder for $label"))
+    val output = SignallingRef[IO].of(default).toResource
+
+    (element, output).mapN((e, o) => Component(e, o))
   }
 
   def textbox(t: Textbox): UI[String] = {
     val Textbox(label, default, style) = t
-    div(p("textbox placeholder for $label"))
+    val element = div(p("textbox placeholder for $label"))
+    val output = SignallingRef[IO].of(default).toResource
+
+    (element, output).mapN((e, o) => Component(e, o))
   }
 
   def above[A, B](t: UI[A], b: UI[B]): UI[(A, B)] = {
-    div(t, b)
+    for {
+      top <- t
+      bot <- b
+      element = div(top.element, bot.element)
+      output = (top.output, bot.output).tupled
+      c <- element.map(e => Component(e, output))
+    } yield c
   }
 }