From e6ce6f18ffd6bf2ee1943d7326e594feff02b8fe Mon Sep 17 00:00:00 2001
From: Arman Bilge <armanbilge@gmail.com>
Date: Mon, 17 Apr 2023 03:21:09 +0000
Subject: [PATCH] Enable modifiers to be reified

Co-authored-by: =?UTF-8?q?Jakub=20Koz=C5=82owski?= <kubukoz@gmail.com>
---
 .../src/main/scala/calico/html/Modifier.scala | 22 +++++++++++++++++++
 .../src/test/scala/calico/SyntaxSuite.scala   |  5 ++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/calico/src/main/scala/calico/html/Modifier.scala b/calico/src/main/scala/calico/html/Modifier.scala
index 2b98203e..8aa3858a 100644
--- a/calico/src/main/scala/calico/html/Modifier.scala
+++ b/calico/src/main/scala/calico/html/Modifier.scala
@@ -37,6 +37,28 @@ trait Modifier[F[_], E, A]:
   inline final def contramap[B](inline f: B => A): Modifier[F, E, B] =
     (b: B, e: E) => outer.modify(f(b), e)
 
+  extension (a: A)
+    inline final def toMod[E0 <: E]: Mod[F, E0] =
+      Mod(a)(using this.asInstanceOf[Modifier[F, E0, A]])
+
+/**
+ * A reified modifier
+ */
+trait Mod[F[_], E]:
+  protected type M
+  protected def mod: M
+  protected def modifier: Modifier[F, E, M]
+
+object Mod:
+  def apply[F[_], E, A](a: A)(using Modifier[F, E, A]): Mod[F, E] =
+    new:
+      type M = A
+      def mod = a
+      def modifier = summon[Modifier[F, E, M]]
+
+  given [F[_], E, E0 <: E]: Modifier[F[_], E0, Mod[F, E]] = (m, e) =>
+    m.modifier.modify(m.mod, e)
+
 object Modifier:
   inline given forUnit[F[_], E]: Modifier[F, E, Unit] =
     _forUnit.asInstanceOf[Modifier[F, E, Unit]]
diff --git a/calico/src/test/scala/calico/SyntaxSuite.scala b/calico/src/test/scala/calico/SyntaxSuite.scala
index 376f36d6..afa95366 100644
--- a/calico/src/test/scala/calico/SyntaxSuite.scala
+++ b/calico/src/test/scala/calico/SyntaxSuite.scala
@@ -22,6 +22,7 @@ import calico.syntax.*
 import cats.effect.*
 import cats.syntax.all.*
 import fs2.concurrent.*
+import fs2.dom.*
 
 class SyntaxSuite:
 
@@ -30,10 +31,12 @@ class SyntaxSuite:
   def nodeSignal: SignallingRef[IO, Resource[IO, fs2.dom.Node[IO]]] = ???
   def nodeOptionSignal: SignallingRef[IO, Option[Resource[IO, fs2.dom.Node[IO]]]] = ???
 
+  def mod = (cls := "bar").toMod[Node[IO]]
+
   def signalModifiers =
     div(
       stringSignal,
       stringOptionSignal,
       nodeSignal,
       nodeOptionSignal
-    ).flatTap(_.modify(cls := "foo"))
+    ).flatTap(_.modify(cls := "foo")).flatTap(_.modify(mod))