• Example Search
• Project Search

• Java
• Python
• JavaScript
• TypeScript
• C++
• Scala
• Blog

• skunk-master
  • .github
    • workflows
      • build.yml
      • release.yml
  • LICENSE
  • project
    • build.properties
    • project
      • plugins.sbt
    • plugins.sbt
  • .gitattributes
  • CHANGELOG.md
  • README.md
  • world
    • server.key
    • README.md
    • server.crt
    • Dockerfile
  • build.sbt
  • .gitignore
  • modules
    • circe
      • src
        • main
          • scala
            • JsonCodecs.scala
    • example
      • src
        • main
          • scala
            • Minimal1.scala
            • NatchezHttp4sModule.scala
            • Channel.scala
            • Error.scala
            • Math1.scala
            • Values.scala
            • Main.scala
            • Join.scala
            • Http4s.scala
            • Math2.scala
            • Minimal3.scala
            • Minimal2.scala
            • Transaction.scala
    • refined
      • src
        • main
          • scala
            • codec
              • NumericCodecs.scala
    • tests
      • src
        • main
          • scala
            • ffstest
              • FFramework.scala
        • test
          • scala
            • CommandTest.scala
            • StartupTest.scala
            • codec
              • BinaryCodecTest.scala
              • EnumCodecTest.scala
              • NumericCodecTest.scala
              • JsonCodecTest.scala
              • TextCodecTest.scala
              • BooleanCodecTest.scala
              • UuidCodecTest.scala
              • TemporalCodecTest.scala
              • CodecTest.scala
            • ExtendedQueryErrorTest.scala
            • SkunkTest.scala
            • SslTest.scala
            • TransactionStatusTest.scala
            • ListTest.scala
            • ErrorResponseTest.scala
            • PoolTest.scala
            • QuickQueryErrorTest.scala
    • core
      • src
        • main
          • scala-2.12
            • utll
              • package.scala
          • scala
            • Decoder.scala
            • PreparedCommand.scala
            • Statement.scala
            • Channel.scala
            • codec
              • BooleanCodec.scala
              • UuidCodec.scala
              • BinaryCodecs.scala
              • AllCodecs.scala
              • EnumCodec.scala
              • TemporalCodecs.scala
              • NumericCodecs.scala
              • TextCodecs.scala
            • Cursor.scala
            • Command.scala
            • Session.scala
            • package.scala
            • net
              • SSLNegotiation.scala
              • package.scala
              • Protocol.scala
              • AbstractMessageSocket.scala
              • message
                • AuthenticationRequest.scala
                • ParseComplete.scala
                • PortalSuspended.scala
                • AuthenticationKerberosV5.scala
                • Terminate.scala
                • ErrorResponse.scala
                • AuthenticationSSPI.scala
                • AuthenticationSASLContinue.scala
                • package.scala
                • NoticeResponse.scala
                • FrontendMessage.scala
                • AuthenticationSASL.scala
                • Flush.scala
                • Execute.scala
                • AuthenticationCleartextPassword.scala
                • RowDescription.scala
                • Sync.scala
                • StartupMessage.scala
                • AuthenticationMD5Password.scala
                • AuthenticationSASLFinal.scala
                • BackendMessage.scala
                • CommandComplete.scala
                • ParameterDescription.scala
                • Describe.scala
                • Close.scala
                • ParameterStatus.scala
                • NotificationResponse.scala
                • Parse.scala
                • RowData.scala
                • Bind.scala
                • BindComplete.scala
                • UnknownMessage.scala
                • CloseComplete.scala
                • AuthenticationSCMCredential.scala
                • Query.scala
                • AuthenticationOk.scala
                • NoData.scala
                • PasswordMessage.scala
                • ReadyForQuery.scala
                • AuthenticationGSS.scala
                • BackendKeyData.scala
                • AuthenticationGSSContinue.scala
              • MessageSocket.scala
              • BufferedMessageSocket.scala
              • protocol
                • Unroll.scala
                • Exchange.scala
                • package.scala
                • Execute.scala
                • Startup.scala
                • Describe.scala
                • Close.scala
                • Parse.scala
                • Bind.scala
                • Query.scala
                • Prepare.scala
              • BitVectorSocket.scala
            • SSL.scala
            • PreparedQuery.scala
            • Encoder.scala
            • util
              • Text.scala
              • Twiddler.scala
              • Pretty.scala
              • Recycler.scala
              • Namer.scala
              • Pool.scala
              • Typer.scala
            • Void.scala
            • syntax
              • ListOps.scala
              • IdOps.scala
              • AllOps.scala
              • StringContextOps.scala
            • exception
              • NoDataException.scala
              • UnknownTypeException.scala
              • StartupException.scala
              • UnknownOidException.scala
              • package.scala
              • DecodeException.scala
              • SkunkException.scala
              • ProtocolError.scala
              • UnexpectedColumnsException.scala
              • ColumnAlignmentException.scala
              • PostgresErrorException.scala
            • data
              • TypedRowDescription.scala
              • Completion.scala
              • Identifier.scala
              • Notification.scala
              • Type.scala
              • TransactionStatus.scala
            • SqlState.scala
            • Fragment.scala
            • Query.scala
            • Codec.scala
            • Transaction.scala
          • scala-2.13
            • utll
              • package.scala
    • docs
      • src
        • main
          • paradox
            • tutorial
              • Setup.md
              • Channels.md
              • Transactions.md
              • Command.md
              • Tracing.md
              • Index.md
              • Query.md
            • index.md
            • reference
              • TwiddleLists.md
              • SchemaTypes.md
              • Fragments.md
              • Sessions.md
              • Concurrency.md
              • Index.md
              • Identifiers.md
              • Encoders.md
    • macros
      • src
        • main
          • scala
            • util
              • Origin.scala
  • docker-compose.yml

// Copyright (c) 2018-2020 by Rob Norris
// This software is licensed under the MIT License (MIT).
// For more information see LICENSE or https://opensource.org/licenses/MIT

package example

import cats.Monad
import cats.effect.{ ExitCode, IO, IOApp, Resource }
import skunk.Session
import skunk.implicits._
import skunk.codec.numeric.{ int4, float8 }
import natchez.Trace.Implicits.noop

object Math2 extends IOApp {

  val session: Resource[IO, Session[IO]] =
    Session.single(
      host     = "localhost",
      port     = 5432,
      user     = "jimmy",
      database = "world",
      password = Some("banana"),
      debug    = true
    )

  // An algebra for doing math.
  trait Math[F[_]] {
    def add(a: Int, b: Int): F[Int]
    def sqrt(d: Double): F[Double]
  }

  object Math {

    object Statements {
      val add  = sql"select $int4 + $int4".query(int4)
      val sqrt = sql"select sqrt($float8)".query(float8)
    }

    def fromSession[F[_]: Monad](sess: Session[F]): Resource[F, Math[F]] =
      for {
        pAdd  <- sess.prepare(Statements.add)
        pSqrt <- sess.prepare(Statements.sqrt)
      } yield
        new Math[F] {
          def add(a: Int, b: Int) = pAdd.unique(a ~ b)
          def sqrt(d: Double)     = pSqrt.unique(d)
        }

  }

  def run(args: List[String]): IO[ExitCode] =
    session.flatMap(Math.fromSession(_)).use { m =>
      for {
        n  <- m.add(42, 71)
        d  <- m.sqrt(2)
        d2 <- m.sqrt(42)
        _  <- IO(println(s"The answers were $n and $d and $d2"))
      } yield ExitCode.Success
    }

}