Initial cache implementation

.gitignore

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+# bloop and metals
+.bloop
+.bsp
+
+# metals
+project/metals.sbt
+.metals
+
+# vs code
+.vscode
+
+# scala 3
+.tasty
+
+# sbt
+project/project/
+project/target/
+target/
+
+# other
+.history
+.scala_dependencies
+.cache-main
+
+#general
+*.class

.scalafmt.conf

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+version = "2.7.5"
+lineLength = 100

build.sbt

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+lazy val CatsEffectVersion = "2.5.1"
+lazy val ScalaTestVersion = "3.2.5"
+
+lazy val root = (project in file("."))
+  .settings(
+    organization := "io.github.mjftw",
+    name := "scache",
+    version := "0.0.1-SNAPSHOT",
+    scalaVersion := "2.13.4",
+    libraryDependencies ++= Seq(
+      "org.typelevel" %% "cats-effect" % CatsEffectVersion,
+      "org.scalatest" %% "scalatest" % ScalaTestVersion % Test
+    )
+  )

project/build.properties

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+sbt.version=1.5.3

src/main/scala/org/github/mjftw/scache/Cache.scala

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+package org.github.mjftw.scache
+
+import cats.effect.concurrent.Ref
+import cats.effect.Sync
+import cats.implicits._
+
+trait Cache[F[_], A, B] {
+  def put(key: A, value: B): F[Unit]
+  def get(key: A): F[Option[B]]
+}
+
+object Cache {
+  def make[F[_]: Sync, A, B]: F[Cache[F, A, B]] =
+    Ref.of[F, Map[A, B]](Map.empty[A, B]).map { ref =>
+      new Cache[F, A, B] {
+        def put(key: A, value: B) = ref.update(_ + (key -> value))
+        def get(key: A): F[Option[B]] = ref.get.map(_.get(key))
+      }
+    }
+}