#15 - Made generic lenses work using Generic but need to call Generi…

…c.product before
optics-dev · Mar 11, 2014 · 3bfe9e9 · 3bfe9e9
1 parent 9a634b0
commit 3bfe9e9
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Showing 2 changed files with 18 additions and 5 deletions.
diff --git a/core/src/main/scala/monocle/thirdparty/HList.scala b/core/src/main/scala/monocle/thirdparty/HList.scala
@@ -1,7 +1,9 @@
 package monocle.thirdparty
 
 import monocle.{SimpleLens, Iso, Lens}
+import shapeless.HList._
 import shapeless._
+import shapeless.ops.hlist.{ReplaceAt, At}
 
 
 object hlist extends HListInstances
@@ -20,9 +22,16 @@ trait HListInstances {
       hl => hl.head -> hl.tail.head
     )
 
-  def first[S, A, L <: HList](implicit gen : Generic.Aux[S, L], nth : HListNthLensAux[L, shapeless.nat._0.N, A]) = at(shapeless.nat._0)
 
-  def at[S, A, L <: HList](n : Nat)(implicit gen : Generic.Aux[S, L], nth : HListNthLensAux[L, n.N, A]) =
-    SimpleLens[S, A](s => nth.get(gen.to(s)), (s, a) => gen.from(nth.set(gen.to(s))(a)) )
+  def first[S, A, L <: HList](implicit gen: Generic.Aux[S, L],
+                                        at: At.Aux[L, shapeless.nat._0.N, A],
+                                   replace: ReplaceAt.Aux[L, shapeless.nat._0.N, A, (A, L)]) = _at(shapeless.nat._0)
+
+
+
+  def _at[S, A, L <: HList](n : Nat)(implicit gen: Generic.Aux[S, L],
+                                               at: At.Aux[L, n.N, A],
+                                          replace: ReplaceAt.Aux[L, n.N, A, (A, L)]) =
+    SimpleLens[S, A](s => gen.to(s).at(n), (s, a) => gen.from(gen.to(s).updatedAt(n, a)) )
 
 }
diff --git a/examples/src/main/scala/monocle/HListExample.scala b/examples/src/main/scala/monocle/HListExample.scala
@@ -2,6 +2,7 @@ package monocle
 
 import monocle.thirdparty.hlist._
 import shapeless._
+import shapeless.Generic._
 
 object HListExample extends App {
 
@@ -18,9 +19,12 @@ object HListExample extends App {
 
 
   case class Person(name : String, age : Int)
-  val julien = Person("Julien", 27)
+  val character = Person("Julien", 27)
 
-  println( first.get(julien) )
+  implicit val gen = Generic.product[Person]
+
+  println( first.get(character) )
+  println( first.set(character, "Roger"))