Merge pull request #90 from Kevin-Lee/task/89/add-writer-syntax

Close #89 - Add writer syntax

src/main/scala/just/fp/syntax/WriterSyntax.scala

@@ -0,0 +1,22 @@
+package just.fp.syntax
+
+import just.fp.Writer
+
+import scala.language.implicitConversions
+
+/**
+  * @author Kevin Lee
+  * @since 2019-10-02
+  */
+object WriterOps {
+  final class ToWriter[A](val a: A) extends AnyVal {
+    def writer[W](w: W): Writer[W, A] = Writer(w, a)
+  }
+}
+
+trait WriterSyntax {
+  import WriterOps._
+
+  @SuppressWarnings(Array("org.wartremover.warts.ImplicitConversion"))
+  implicit final def toWriter[A](a: A): ToWriter[A] = new ToWriter(a)
+}

src/main/scala/just/fp/syntax/package.scala

@@ -9,3 +9,4 @@ package object syntax
      with OptionSyntax
      with EitherSyntax
      with SemiGroupSyntax
+     with WriterSyntax

src/test/scala/just/fp/syntax/WriterSyntaxSpec.scala

@@ -0,0 +1,28 @@
+package just.fp.syntax
+
+import hedgehog._
+import hedgehog.runner._
+
+import just.fp.Gens
+
+/**
+  * @author Kevin Lee
+  * @since 2019-10-02
+  */
+object WriterSyntaxSpec extends Properties {
+  override def tests: List[Test] = List(
+    property("test value.writer(w) syntax", testValueWriter)
+  )
+
+  def testValueWriter: Property = for {
+    a <- Gens.genIntFromMinToMax.log("a")
+    w <- Gens.genUnicodeString.log("w")
+  } yield {
+    import just.fp._
+
+    val expected = Writer(w, a)
+    val actual = a.writer(w)
+
+    actual ==== expected
+  }
+}