Merge pull request disneystreaming#1873 from ghostbuster91/validated-prism

Add asSurjection to ValidatedNewtype

Author: ghostbuster91

CHANGELOG.md

@@ -5,6 +5,10 @@ When adding entries, please treat them as if they could end up in a release any
 
 Thank you!
 
+# 0.18.47
+
+* core: Add `asSurjection` method to `ValidatedNewtype` class (see [#1873](https://github.com/disneystreaming/smithy4s/pull/1873))
+
 # 0.18.46
 
 * core: Set the Accept header via the HttpUnaryClientCodecs  (see [#1864](https://github.com/disneystreaming/smithy4s/pull/1864))

modules/bootstrapped/test/src/smithy4s/ValidatedNewtypesSpec.scala

@@ -54,6 +54,32 @@ class ValidatedNewtypesSpec() extends munit.FunSuite {
     )
   }
 
+  test("should allow to derive typeclasses in a generic way") {
+    trait MyCodec[A] {
+      def decode(str: String): Either[String, A]
+      def encode(a: A): String
+    }
+
+    object MyCodec {
+      implicit val stringCodec: MyCodec[String] = new MyCodec[String] {
+        def decode(str: String): Either[String, String] = Right(str)
+        def encode(a: String): String = a
+      }
+    }
+
+    def genericCodec[A, B: MyCodec](s: Surjection[B, A]) = new MyCodec[A] {
+      def decode(str: String): Either[String, A] =
+        implicitly[MyCodec[B]].decode(str).flatMap(s.to)
+      def encode(a: A): String = implicitly[MyCodec[B]].encode(s.from(a))
+    }
+
+    val accountIdCodec =
+      genericCodec[AccountId, String](implicitly[Surjection[String, AccountId]])
+
+    expect.same(accountIdCodec.encode(AccountId.unsafeApply(id1)), id1)
+    expect.same(accountIdCodec.decode(id1), Right(AccountId.unsafeApply(id1)))
+  }
+
   type DeviceId = DeviceId.Type
   object DeviceId extends ValidatedNewtype[String] {
 

modules/core/src-2/ValidatedNewtype.scala

@@ -29,6 +29,12 @@ abstract class ValidatedNewtype[A] extends AbstractNewtype[A] { self =>
     @inline final def value: A = ValidatedNewtype.this.value(self)
   }
 
+  implicit val asSurjection: Surjection[A, Type] =
+    new ValidatedNewtype.Make[A, Type] {
+      def to(a: A): Either[String, Type] = self.apply(a)
+      def from(t: Type): A = value(t)
+    }
+
   def unapply(t: Type): Some[A] = Some(t.value)
 
   object hint {
@@ -37,5 +43,5 @@ abstract class ValidatedNewtype[A] extends AbstractNewtype[A] { self =>
 }
 
 object ValidatedNewtype {
-  private[smithy4s] trait Make[A, B] extends Bijection[A, B]
+  private[smithy4s] trait Make[A, B] extends Surjection[A, B]
 }

modules/core/src-3/ValidatedNewtype.scala

@@ -30,6 +30,12 @@ abstract class ValidatedNewtype[A] extends AbstractNewtype[A] { self =>
 
   extension (orig: Type) def value: A = orig
 
+  implicit val asSurjection: Surjection[A, Type] =
+    new ValidatedNewtype.Make[A, Type] {
+      def to(a: A): Either[String, Type] = self.apply(a)
+      def from(t: Type): A = value(t)
+    }
+
   def unapply(orig: Type): Some[A] = Some(orig.value)
 
   object hint {
@@ -38,5 +44,5 @@ abstract class ValidatedNewtype[A] extends AbstractNewtype[A] { self =>
 }
 
 object ValidatedNewtype {
-  private[smithy4s] trait Make[A, B] extends Bijection[A, B]
+  private[smithy4s] trait Make[A, B] extends Surjection[A, B]
 }