pre-commit

src/main/scala/gs/fizzbuzz/Condition.scala

@@ -1,18 +1,60 @@
 package gs.fizzbuzz
 
 import cats.Applicative
+import cats.Monoid
 
-trait Condition[F[_], Input, Output]:
+trait Condition[F[_], Input]:
   def matches(input: Input): F[Boolean]
-  def output: Output
 end Condition
 
 object Condition:
 
-  final class Noop[F[_]: Applicative, Input] extends Condition[F, Input, Nothing]:
-    override def matches(input: Input): F[Boolean] = 
+  def apply[F[_]: Applicative, Input](
+    comparison: Input,
+    operator: Monoid[Input]
+  )(
+    using
+    CanEqual[Input, Input]
+  ): Condition[F, Input] =
+    new DefaultCondition[F, Input](comparison, operator)
+
+  def forInt[F[_]: Applicative](
+    comparison: Int,
+    operator: (Int, Int) => Int
+  ): Condition[F, Int] =
+    new DefaultCondition[F, Int](comparison, makeIntMonoid(operator))
+
+  def forLong[F[_]: Applicative](
+    comparison: Long,
+    operator: (Long, Long) => Long
+  ): Condition[F, Long] =
+    new DefaultCondition[F, Long](comparison, makeLongMonoid(operator))
+
+  private def makeIntMonoid(op: (Int, Int) => Int): Monoid[Int] =
+    new Monoid[Int] {
+      override def empty: Int = 0
+
+      override def combine(
+        x: Int,
+        y: Int
+      ): Int = op(x, y)
+    }
+
+  private def makeLongMonoid(op: (Long, Long) => Long): Monoid[Long] =
+    new Monoid[Long] {
+      override def empty: Long = 0
+
+      override def combine(
+        x: Long,
+        y: Long
+      ): Long = op(x, y)
+    }
+
+  def noop[F[_]: Applicative, Input]: Condition[F, Input] = new Noop[F, Input]
+
+  final class Noop[F[_]: Applicative, Input] extends Condition[F, Input]:
+
+    override def matches(input: Input): F[Boolean] =
       Applicative[F].pure(false)
-    override def output: Nothing = 
-      throw new IllegalStateException("No-op condition cannot produce output.")
 
 end Condition

src/main/scala/gs/fizzbuzz/DefaultCondition.scala

@@ -3,13 +3,15 @@ package gs.fizzbuzz
 import cats.Applicative
 import cats.Monoid
 
-final class DefaultCondition[F[_]: Applicative, Input, Out](
+final class DefaultCondition[F[_]: Applicative, Input](
   val comparison: Input,
-  val output: Out,
   val operator: Monoid[Input]
-)(using CanEqual[Input, Input]) extends Condition[F, Input, Out]:
+)(
+  using
+  CanEqual[Input, Input]
+) extends Condition[F, Input]:
 
-  override def matches(input: Input): F[Boolean] = 
+  override def matches(input: Input): F[Boolean] =
     Applicative[F].pure(
       operator.combine(input, comparison) == operator.empty
     )

src/main/scala/gs/fizzbuzz/DefaultFizzBuzz.scala

@@ -1,26 +1,21 @@
 package gs.fizzbuzz
 
-import cats.syntax.all.*
-import fs2.Pipe
 import cats.FlatMap
+import cats.syntax.all.*
 
-class DefaultFizzBuzz[F[_]: FlatMap, Input, Out](
-  val fizzCondition: Condition[F, Input, Out],
-  val buzzCondition: Condition[F, Input, Out]
-) extends FizzBuzz[F, Input, Out]:
-  def evaluate(input: Input): F[Result[Out]] = 
+class DefaultFizzBuzz[F[_]: FlatMap, Input](
+  val fizzCondition: Condition[F, Input],
+  val buzzCondition: Condition[F, Input]
+) extends FizzBuzz[F, Input]:
+
+  def evaluate(input: Input): F[Result] =
     for
       fizz <- fizzCondition.matches(input)
       buzz <- buzzCondition.matches(input)
-    yield 
-      if fizz && buzz then
-        Result.FizzBuzz(fizzCondition.output, buzzCondition.output)
-      else if fizz then
-        Result.Fizz(fizzCondition.output)
-      else if buzz then
-        Result.Buzz(buzzCondition.output)
-      else
-        Result.Unmatched
+    yield
+      if fizz && buzz then Result.FizzBuzz
+      else if fizz then Result.Fizz
+      else if buzz then Result.Buzz
+      else Result.Unmatched
 
-  def pipe(): Pipe[F, Input, Result[Out]] = in => in.evalMap(evaluate)
 end DefaultFizzBuzz

src/main/scala/gs/fizzbuzz/FizzBuzz.scala

@@ -1,8 +1,45 @@
 package gs.fizzbuzz
 
+import cats.Applicative
+import cats.FlatMap
 import fs2.Pipe
 
-trait FizzBuzz[F[_], Input, Out]:
-  def evaluate(input: Input): F[Result[Out]] 
-  def pipe(): Pipe[F, Input, Result[Out]]
+trait FizzBuzz[F[_], Input]:
+  def evaluate(input: Input): F[Result]
+  def pipe(): Pipe[F, Input, Result] = in => in.evalMap(evaluate)
+end FizzBuzz
+
+object FizzBuzz:
+
+  def apply[F[_]: FlatMap, Input](
+    fizzCondition: Condition[F, Input],
+    buzzCondition: Condition[F, Input]
+  ): FizzBuzz[F, Input] =
+    new DefaultFizzBuzz[F, Input](fizzCondition, buzzCondition)
+
+  def forInt[F[_]: FlatMap: Applicative](
+    fizz: Int,
+    buzz: Int,
+    f: (Int, Int) => Int
+  ): FizzBuzz[F, Int] = new DefaultFizzBuzz[F, Int](
+    fizzCondition = Condition.forInt[F](fizz, f),
+    buzzCondition = Condition.forInt[F](buzz, f)
+  )
+
+  def forLong[F[_]: FlatMap: Applicative](
+    fizz: Long,
+    buzz: Long,
+    f: (Long, Long) => Long
+  ): FizzBuzz[F, Long] = new DefaultFizzBuzz[F, Long](
+    fizzCondition = Condition.forLong[F](fizz, f),
+    buzzCondition = Condition.forLong[F](buzz, f)
+  )
+
+  def noop[F[_]: Applicative, Input]: FizzBuzz[F, Input] = new Noop[F, Input]
+
+  final class Noop[F[_]: Applicative, Input] extends FizzBuzz[F, Input]:
+
+    override def evaluate(input: Input): F[Result] =
+      Applicative[F].pure(Result.Unmatched)
+
 end FizzBuzz

src/main/scala/gs/fizzbuzz/Main.scala

@@ -1,42 +1,28 @@
 package gs.fizzbuzz
 
-import cats.Monoid
+import cats.effect.ExitCode
 import cats.effect.IO
 import cats.effect.IOApp
-import cats.effect.ExitCode
 
 object Main extends IOApp:
-  override def run(args: List[String]): IO[ExitCode] = 
-    val op: Monoid[Long] = new Monoid[Long] {
-      override def empty: Long = 0L
-      override def combine(x: Long, y: Long): Long = x % y
-    }
 
-    val fizzCond: Condition[IO, Long, String] = new DefaultCondition(
-      comparison = 3L,
-      output = "Fizz",
-      operator = op
+  override def run(args: List[String]): IO[ExitCode] =
+    val fb = FizzBuzz.forLong[IO](
+      fizz = 3,
+      buzz = 5,
+      f = (
+        x,
+        y
+      ) => x % y
     )
 
-    val buzzCond: Condition[IO, Long, String] = new DefaultCondition(
-      comparison = 5L,
-      output = "Buzz",
-      operator = op
-    )
-
-    val fb: FizzBuzz[IO, Long, String] = new DefaultFizzBuzz[IO, Long, String](
-      fizzCondition = fizzCond,
-      buzzCondition = buzzCond
-    )
-
-    for 
+    for
       ex1 <- fb.evaluate(15)
       ex2 <- fb.evaluate(9)
       ex3 <- fb.evaluate(20)
       ex4 <- fb.evaluate(13)
-      _ <- IO.println(ex1)
-      _ <- IO.println(ex2)
-      _ <- IO.println(ex3)
-      _ <- IO.println(ex4)
-    yield
-      ExitCode.Success
+      _   <- IO.println(ex1)
+      _   <- IO.println(ex2)
+      _   <- IO.println(ex3)
+      _   <- IO.println(ex4)
+    yield ExitCode.Success

src/main/scala/gs/fizzbuzz/Result.scala

@@ -1,13 +1,12 @@
 package gs.fizzbuzz
 
-sealed trait Result[+Out]
+sealed trait Result
 
 object Result:
 
-  case class Fizz[Out](fizz: Out) extends Result[Out]
-  case class Buzz[Out](buzz: Out) extends Result[Out]
-  case class FizzBuzz[Out](fizz: Out, buzz: Out) extends Result[Out]
-  case object Unmatched extends Result[Nothing]:
-    override def toString(): String = "unmatched"
+  case object Fizz      extends Result
+  case object Buzz      extends Result
+  case object FizzBuzz  extends Result
+  case object Unmatched extends Result
 
 end Result