Initial commit

.gitignore

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+.bsp/
+target/

CHANGELOG

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+Version 0.1.0 (2021-MM-DD)
+--------------------------
+Initial release

LICENSE

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+           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+                   Version 2, December 2004
+
+Copyright (C) 2020 Anton Parkhomenko <[email protected]>
+
+Everyone is permitted to copy and distribute verbatim or modified
+copies of this license document, and changing it is allowed as long
+as the name is changed.
+
+           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+  TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+0. You just DO WHAT THE FUCK YOU WANT TO.

README.md

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+# otus-bats
+
+## Quickstart
+
+```bash
+$ sbt assembly
+```
+
+## Copyright and License
+
+           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+                   Version 2, December 2004
+
+Copyright (C) 2021 Anton Parkhomenko <[email protected]>
+
+Everyone is permitted to copy and distribute verbatim or modified
+copies of this license document, and changing it is allowed as long
+as the name is changed.
+
+           DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
+  TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+0. You just DO WHAT THE FUCK YOU WANT TO.
+
+[license]: http://www.wtfpl.net/

build.sbt

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+lazy val root = project.in(file("."))
+  .settings(
+    name := "otusbats",
+    version := "0.1.0-rc1",
+    organization := "me.chuwy",
+    scalaVersion := "2.13.5"
+  )
+  .settings(BuildSettings.buildSettings)
+  .settings(BuildSettings.scalifySettings)
+  .settings(libraryDependencies ++= Dependencies.all)
+  .settings(BuildSettings.helpersSettings)
+

project/BuildSettings.scala

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+// SBT
+import sbt._
+import Keys._
+
+/**
+ * To enable any of these you need to explicitly add Settings value to build.sbt
+ */
+object BuildSettings {
+
+  // Makes package (build) metadata available withing source code
+  lazy val scalifySettings = Seq(
+    sourceGenerators in Compile += Def.task {
+      val file = (sourceManaged in Compile).value / "settings.scala"
+    IO.write(file, """package me.chuwy.otusbats.generated
+                      |object ProjectMetadata {
+                      |  val version = "%s"
+                      |  val name = "%s"
+                      |  val organization = "%s"
+                      |  val scalaVersion = "%s"
+                      |}
+                      |""".stripMargin.format(version.value, name.value, organization.value, scalaVersion.value))
+      Seq(file)
+    }.taskValue
+  )
+
+  lazy val buildSettings = Seq[Setting[_]](
+    addCompilerPlugin("org.typelevel" %% "kind-projector" % "0.13.0" cross CrossVersion.full)
+  )
+
+
+  lazy val helpersSettings = Seq[Setting[_]](
+    initialCommands := "import me.chuwy.otusbats._"
+  )
+}

project/Dependencies.scala

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+import sbt._
+
+object Dependencies {
+
+  object V {
+    // Scala
+    val circe            = "0.13.0"
+    val http4s           = "0.21.13"
+    // Scala (test only)
+    val specs2           = "4.10.5"
+    val scalaCheck       = "1.15.1"
+  }
+
+  // Scala
+  val all = List(
+    "io.circe"                   %% "circe-parser"         % V.circe,
+    "org.http4s"                 %% "http4s-dsl"           % V.http4s,
+
+    "org.specs2"                 %% "specs2-core"          % V.specs2         % Test,
+    "org.specs2"                 %% "specs2-scalacheck"    % V.specs2         % Test,
+    "org.scalacheck"             %% "scalacheck"           % V.scalaCheck     % Test
+  )
+}

project/build.properties

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+sbt.version=1.4.6

project/plugins.sbt

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+addSbtPlugin("io.github.davidgregory084" % "sbt-tpolecat" % "0.1.16")

src/main/scala/me.chuwy/otusbats/Example.scala

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+package me.chuwy.otusbats
+
+import cats.Show
+import cats.implicits._
+
+object Example {
+
+  def example[A: Show, B: Show](a: A, b: B) =
+    show"A is $a, B is $b"
+
+  def example[A, B](implicit eva: Show[A], evb: Show[B]) = ???
+
+}

src/main/scala/me.chuwy/otusbats/Functor.scala

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+package me.chuwy.otusbats
+
+import cats.Mo
+
+trait Functor[F[_]] {
+  def map[A, B](fa: F[A])(f: A => B): F[B]
+}
+
+object Functor {
+  // 1. Instances
+  implicit val optionFunctor: Functor[Option] =
+    new Functor[Option] {
+      def map[A, B](fa: Option[A])(f: A => B): Option[B] =
+        fa match {
+          case Some(value) => Some(f(value))
+          case None => None
+        }
+    }
+
+  implicit val listFunctor: Functor[List] =
+    new Functor[List] {
+      def map[A, B](fa: List[A])(f: A => B): List[B] =
+        fa.map(f)
+    }
+
+  val e: Either[String, Int] = Right(3)
+
+  val a: Option[Int] = ???
+
+  // val list = List(Some(1), None, Some(3))
+  // list.map { option => option.map(f) }
+  // nested(list)(i => i.toString)
+
+  def apply[F[_]](implicit ev: Functor[F]): Functor[F] = ev
+
+  // 2. Combinators
+
+  def nested[F[_]: Functor, G[_]: Functor, A, B](fga: F[G[A]])(f: A => B): F[G[B]] =
+    Functor[F].map(fga) { ga =>
+      Functor[G].map(ga)(f)
+    }
+
+  case class NeFunctor[A](a: A, counter: Int) {
+    def map[B](f: A => B): NeFunctor[B] =
+      NeFunctor(f(a), counter + 1)
+  }
+
+
+
+}

src/main/scala/me.chuwy/otusbats/Monad.scala

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+package me.chuwy.otusbats
+
+trait Monad[F[_]] extends Functor[F] { self =>
+  def flatMap[A, B](fa: F[A])(f: A => F[B]): F[B]
+
+  def point[A](a: A): F[A]
+
+  def flatten[A](fa: F[F[A]]): F[A]
+}
+
+object Monad {
+
+}

src/main/scala/me.chuwy/otusbats/Monoid.scala

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+package me.chuwy.otusbats
+
+trait Monoid[A] extends Semigroup[A] {
+  def zero: A
+}
+
+object Monoid {
+}

src/main/scala/me.chuwy/otusbats/Order.scala

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+package me.chuwy.otusbats
+
+trait Order[A] {
+  def compare(x: A, y: A): Option[Boolean]
+}
+
+

src/main/scala/me.chuwy/otusbats/Semigroup.scala

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+package me.chuwy.otusbats
+
+trait Semigroup[A] {
+  def combine(x: A, y: A): A
+}
+
+object Semigroup {
+
+  implicit val semigroupInt = new Semigroup[Int] {
+    override def combine(x: Int, y: Int): Int = x + y
+  }
+}

src/main/scala/me.chuwy/otusbats/Show.scala

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+package me.chuwy.otusbats
+
+
+trait Show[A] {
+  def show(a: A): String
+}
+
+object Show {
+
+  // 1.1 Instances
+
+  implicit val stringShow: Show[String] =
+    new Show[String] {
+      def show(a: String): String = a
+    }
+
+  implicit val intShow: Show[Int] =
+    new Show[Int] {
+      def show(a: Int): String = a.toString
+    }
+
+
+  // 1.2 Instances with conditional implicit
+
+  implicit def listShow[A](implicit ev: Show[A]): Show[List[A]] =
+    new Show[List[A]] {
+      def show(as: List[A]): String = "[" ++ as.map(a => ev.show(a)).mkString(",") ++ "]"
+    }
+
+
+  // 2. Summoner
+
+  def apply[A](implicit ev: Show[A]): Show[A] = ev
+
+  // 3. Syntax extensions
+
+  implicit class ShowOps[A](a: A) {
+    def show(implicit ev: Show[A]): String =
+      ev.show(a)
+  }
+
+  // 4. Helper constructors
+
+}