Packages

•  package root
•  package scala
•  package scodec
•  package skunk

  Skunk is a functional data access layer for Postgres.

  Skunk is a functional data access layer for Postgres.

  Design principles:

  • Skunk doesn't use JDBC. It speaks the Postgres wire protocol. It will not work with any other database back end.
  • Skunk is asynchronous all the way down, via cats-effect, fs2, and ultimately nio. The high-level network layers (Protocol and Session) are safe to use concurrently.
  • Serialization to and from schema types is not typeclass-based, so there are no implicit derivations. Codecs are explicit, like parser combinators.
  • I'm not sweating arity abstraction that much. Pass a ~ b ~ c for three args and Void if there are no args. This may change in the future but it's fine for now.
  • Skunk uses Resource for lifetime-managed objects, which means it takes some discipline to avoid leaks, especially when working concurrently. May or may not end up being problematic.
  • I'm trying to write good Scaladoc this time.

  A minimal example follows. We construct a Resource that yields a Session, then use it.

  package example
  
  import cats.effect._
  import skunk._
  import skunk.implicits._
  import skunk.codec.numeric._
  
  object Minimal extends IOApp {
  
    val session: Resource[IO, Session[IO]] =
      Session.single(
        host     = "localhost",
        port     = 5432,
        user     = "postgres",
        database = "world",
      )
  
    def run(args: List[String]): IO[ExitCode] =
      session.use { s =>
        for {
          n <- s.unique(sql"select 42".query(int4))
          _ <- IO(println(s"The answer is $n."))
        } yield ExitCode.Success
      }
  
  }

  Continue reading for an overview of the library. It's pretty small.

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