Expand syntax package to cover ZIO

- Syntax now available with ZIO rather than IO
- Changed ZIO.require to return ZIO, not IO
- Fixed type parameters on RIO.require

Fixes #1445

core/shared/src/main/scala/zio/IO.scala

@@ -390,7 +390,7 @@ object IO {
    * @see See [[zio.ZIO.require]]
    */
   final def require[E, A](error: E): IO[E, Option[A]] => IO[E, A] =
-    ZIO.require[E, A](error)
+    ZIO.require[Any, E, A](error)
 
   /**
    * @see See [[zio.ZIO.reserve]]

core/shared/src/main/scala/zio/RIO.scala

@@ -446,8 +446,8 @@ object RIO {
   /**
    * @see See [[zio.ZIO.require]]
    */
-  final def require[R, A](error: Throwable): IO[Throwable, Option[A]] => IO[Throwable, A] =
-    ZIO.require(error)
+  final def require[A](error: Throwable): IO[Throwable, Option[A]] => IO[Throwable, A] =
+    ZIO.require[Any, Throwable, A](error)
 
   /**
    * @see See [[zio.ZIO.reserve]]

core/shared/src/main/scala/zio/Task.scala

@@ -401,7 +401,7 @@ object Task {
    * @see See [[zio.ZIO.require]]
    */
   final def require[A](error: Throwable): Task[Option[A]] => Task[A] =
-    ZIO.require[Throwable, A](error)
+    ZIO.require[Any, Throwable, A](error)
 
   /**
    * @see See [[zio.ZIO.reserve]]

core/shared/src/main/scala/zio/ZIO.scala

@@ -2230,11 +2230,11 @@ private[zio] trait ZIOFunctions extends Serializable {
     }
 
   /**
-   * Requires that the given `IO[E, Option[A]]` contain a value. If there is no
+   * Requires that the given `ZIO[R, E, Option[A]]` contain a value. If there is no
    * value, then the specified error will be raised.
    */
-  final def require[E, A](error: E): IO[E, Option[A]] => IO[E, A] =
-    (io: IO[E, Option[A]]) => io.flatMap(_.fold[IO[E, A]](fail[E](error))(succeed[A]))
+  final def require[R, E, A](error: E): ZIO[R, E, Option[A]] => ZIO[R, E, A] =
+    (io: ZIO[R, E, Option[A]]) => io.flatMap(_.fold[ZIO[R, E, A]](fail[E](error))(succeed[A]))
 
   /**
    * Acquires a resource, uses the resource, and then releases the resource.

core/shared/src/main/scala/zio/syntax/package.scala

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2017-2019 John A. De Goes and the ZIO Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package zio
+
+import scala.language.implicitConversions
+
+package object syntax {
+  import zio.syntax.ZIOSyntax._
+
+  implicit final def zioEagerCreationSyntax[A](a: A): EagerCreationSyntax[A]  = new EagerCreationSyntax[A](a)
+  implicit final def zioLazyCreationSyntax[A](a: => A): LazyCreationSyntax[A] = new LazyCreationSyntax[A](() => a)
+  implicit final def zioIterableSyntax[R, E, A](zios: Iterable[ZIO[R, E, A]]): IterableSyntax[R, E, A] =
+    new IterableSyntax[R, E, A](zios)
+
+  implicit final def zioTuple2Syntax[R, E, A, B](zios: (ZIO[R, E, A], ZIO[R, E, B])): Tuple2Syntax[R, E, A, B] =
+    new Tuple2Syntax(zios)
+  implicit final def zioTuple3Syntax[R, E, A, B, C](
+    zios: (ZIO[R, E, A], ZIO[R, E, B], ZIO[R, E, C])
+  ): Tuple3Syntax[R, E, A, B, C] =
+    new Tuple3Syntax(zios)
+  implicit final def zioTuple4Syntax[R, E, A, B, C, D](
+    zios: (ZIO[R, E, A], ZIO[R, E, B], ZIO[R, E, C], ZIO[R, E, D])
+  ): Tuple4Syntax[R, E, A, B, C, D] =
+    new Tuple4Syntax(zios)
+}

core/shared/src/main/scala/zio/syntax/zio.scala

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2017-2019 John A. De Goes and the ZIO Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package zio.syntax
+
+import zio.{ Fiber, ZIO }
+
+object ZIOSyntax {
+  final class EagerCreationSyntax[A](val a: A) extends AnyVal {
+    def fail[R]: ZIO[R, A, Nothing]                            = ZIO.fail(a)
+    def require[R, AA]: ZIO[R, A, Option[AA]] => ZIO[R, A, AA] = ZIO.require(a)
+    def succeed[R, E]: ZIO[R, E, A]                            = ZIO.succeed(a)
+  }
+
+  final class LazyCreationSyntax[A](val a: () => A) extends AnyVal {
+    def effectTotal[R, E]: ZIO[R, E, A] = ZIO.effectTotal(a())
+    def sync[R]: ZIO[R, Throwable, A]   = ZIO.effect(a())
+  }
+
+  final class IterableSyntax[R, E, A](val ios: Iterable[ZIO[R, E, A]]) extends AnyVal {
+    def collectAll: ZIO[R, E, Iterable[A]]                 = ZIO.collectAll(ios)
+    def collectAllPar: ZIO[R, E, Iterable[A]]              = ZIO.collectAllPar(ios)
+    def forkAll: ZIO[R, Nothing, Fiber[E, Iterable[A]]]    = ZIO.forkAll(ios)
+    def mergeAll[B](zero: B)(f: (B, A) => B): ZIO[R, E, B] = ZIO.mergeAll(ios)(zero)(f)
+  }
+
+  final class Tuple2Syntax[R, E, A, B](val ios2: (ZIO[R, E, A], ZIO[R, E, B])) extends AnyVal {
+    def map2[C](f: (A, B) => C): ZIO[R, E, C] = ios2._1.flatMap(a => ios2._2.map(f(a, _)))
+  }
+
+  final class Tuple3Syntax[R, E, A, B, C](val ios3: (ZIO[R, E, A], ZIO[R, E, B], ZIO[R, E, C])) extends AnyVal {
+    def map3[D](f: (A, B, C) => D): ZIO[R, E, D] =
+      for {
+        a <- ios3._1
+        b <- ios3._2
+        c <- ios3._3
+      } yield f(a, b, c)
+  }
+
+  final class Tuple4Syntax[R, E, A, B, C, D](
+    val ios4: (ZIO[R, E, A], ZIO[R, E, B], ZIO[R, E, C], ZIO[R, E, D])
+  ) extends AnyVal {
+    def map4[F](f: (A, B, C, D) => F): ZIO[R, E, F] =
+      for {
+        a <- ios4._1
+        b <- ios4._2
+        c <- ios4._3
+        d <- ios4._4
+      } yield f(a, b, c, d)
+  }
+}