Basic Scalaz applicative for ScalaFX Observables.

src/main/scala/org/gerweck/scalafx/util/package.scala

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+package org.gerweck.scalafx
+
+import language.implicitConversions
+
+import scalafx.beans.property._
+import scalafx.beans.value._
+import scalafx.event.subscriptions.Subscription
+import scalafx.scene.Node
+import scalafx.scene.control._
+import scalafx.scene.layout.GridPane
+import scalafx.util.StringConverter
+
+import scalaz._
+import Scalaz._
+
+/** Various implicits and global utilities for ScalaFX work.
+  *
+  * @author Sarah Gerweck <sarah@atscale.com>
+  */
+package object util {
+  type Observable[A] = ObservableValue[A, _]
+
+  implicit val observableApplicative = new Applicative[Observable] {
+    def point[A](a: => A): Observable[A] = {
+      ObjectProperty[A](a)
+    }
+
+    def ap[A, B](fa: => Observable[A])(f: => Observable[A => B]): Observable[B] = {
+      def recalculate: B = (f.value)(fa.value)
+
+      val originalValue = recalculate
+
+      val prop = ObjectProperty[B](originalValue)
+
+      var prevValue = originalValue
+
+      def changeHandler = {
+        val newVal = recalculate
+        if (prevValue != newVal) {
+          prop.value = recalculate
+        }
+      }
+
+      fa onChange changeHandler
+      f onChange changeHandler
+
+      prop
+    }
+  }
+
+  implicit class RichProperty[A](val inner: Property[A, _]) extends AnyVal {
+    def biMap[B <: AnyRef](push: A => B, pull: B => A): ObjectProperty[B] = {
+      val original = push(inner.value)
+      val op = ObjectProperty[B](original)
+      inner onChange {
+        val oldVal = op.value
+        val newVal = push(inner.value)
+        if (oldVal != newVal) {
+          op.value = push(inner.value)
+        }
+      }
+      op onChange {
+        val oldVal = inner.value
+        val newVal = pull(op.value)
+        if (oldVal != newVal) {
+          inner.value = newVal
+        }
+      }
+      op
+    }
+  }
+
+  implicit class RichGridPane(val inner: GridPane) extends AnyVal {
+    def addToRow(ri: Int, children: Node*) = inner.addRow(ri, children map {_.delegate}: _*)
+  }
+}