Infer better type for regular operations on Rule1[_] (#48)

src/main/scala/com/github/zenpie/macrowave/Rule.scala

@@ -12,12 +12,12 @@ sealed abstract class Rule[+T <: HList] {
 
 
   @compileTimeOnly("Calls to method '*' have to be inside a macro invocation!")
-  def *[V >: T <: HList] : Rule[List[V] :: HNil] = compileTime
+  def *[V >: T <: HList](implicit S: SingletonRule[V]) : Rule[List[S.Out] :: HNil] = compileTime
 
   @compileTimeOnly("Calls to method '+' have to be inside a macro invocation!")
-  def +[V >: T <: HList] : Rule[V :: List[V] :: HNil] = compileTime
+  def +[V >: T <: HList](implicit S: SingletonRule[V]) : Rule[S.Out :: List[S.Out] :: HNil] = compileTime
 
   @compileTimeOnly("Calls to method '?' have to be inside a macro invocation!")
-  def ?[V >: T <: HList] : Rule[Option[V] :: HNil] = compileTime
+  def ?[V >: T <: HList](implicit S: SingletonRule[V]) : Rule[Option[S.Out] :: HNil] = compileTime
 
 }

src/main/scala/com/github/zenpie/macrowave/internal/parser/RuleParser.scala

@@ -112,15 +112,15 @@ trait RuleParser extends MacroUtils {
         val x   = helper(r)
         parser.Transform(x, aid, tid)
 
-      case q"($r).*[$rTpt]" =>
+      case q"($r).*[$rTpt]($ev)" =>
         val tid = typeOf(tree)
         val x   = helper(r)
         parser.Kleene(x, tid)
-      case q"($r).+[$rTpt]" =>
+      case q"($r).+[$rTpt]($ev)" =>
         val tid = typeOf(tree)
         val x   = helper(r)
         parser.PClosure(x, tid)
-      case q"($r).?[$rTpt]" =>
+      case q"($r).?[$rTpt]($ev)" =>
         val tid = typeOf(tree)
         val x   = helper(r)
         parser.Optional(x, tid)

src/main/scala/com/github/zenpie/macrowave/package.scala

@@ -13,6 +13,7 @@ package object macrowave {
   val HNil = shapeless.HNil
 
   type Prepend[P <: HList, S <: HList] = shapeless.ops.hlist.Prepend[P, S]
+  type SingletonRule[T] = com.github.zenpie.macrowave.support.SingletonRule[T]
 
   type Rule1[+T] = Rule[T :: HNil]
 

src/main/scala/com/github/zenpie/macrowave/support/SingletonRule.scala

@@ -0,0 +1,31 @@
+package com.github.zenpie.macrowave.support
+
+import com.github.zenpie.macrowave._
+
+trait SingletonRule[T] {
+  type Out
+}
+
+object SingletonRule extends SingletonRuleLowPriorityImplicits {
+
+  type Aux[T, Out0] = SingletonRule[T] {
+    type Out = Out0
+  }
+
+  implicit val hnil: SingletonRule.Aux[HNil, HNil] = new SingletonRule[HNil] {
+    type Out = HNil
+  }
+
+  implicit def hcons1[T]: SingletonRule.Aux[T :: HNil, T] = new SingletonRule[T :: HNil] {
+    type Out = T
+  }
+
+}
+
+trait SingletonRuleLowPriorityImplicits {
+
+  implicit def hconsN[H, T <: HList]: SingletonRule.Aux[H :: T, H :: T] = new SingletonRule[H :: T] {
+    type Out = H :: T
+  }
+
+}