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package io.getquill.monad
import scala.collection.generic.CanBuildFrom
import scala.language.higherKinds
import scala.util.Failure
import scala.util.Success
import scala.util.Try
import io.getquill.context.Context
sealed trait Effect
object Effect {
trait Read extends Effect
trait Write extends Effect
trait Transaction extends Effect
trait IOMonad {
this: Context[_, _] =>
type Effect = io.getquill.monad.Effect
val Effect = io.getquill.monad.Effect
protected case class FromTry[T](t: Try[T]) extends IO[T, Effect]
protected case class Sequence[A, M[X] <: TraversableOnce[X], E <: Effect](in: M[IO[A, E]], cbfIOToResult: CanBuildFrom[M[IO[A, E]], Result[A], M[Result[A]]], cbfResultToValue: CanBuildFrom[M[Result[A]], A, M[A]]) extends IO[M[A], E]
protected case class TransformWith[T, S, E1 <: Effect, E2 <: Effect](io: IO[T, E1], f: Try[T] => IO[S, E2]) extends IO[S, E1 with E2]
protected case class Transactional[T, E <: Effect](io: IO[T, E]) extends IO[T, E with Effect.Transaction]
object IO {
def fromTry[T](result: Try[T]): IO[T, Effect] = FromTry(result)
def sequence[A, M[X] <: TraversableOnce[X], E <: Effect](in: M[IO[A, E]])(implicit cbfIOToResult: CanBuildFrom[M[IO[A, E]], Result[A], M[Result[A]]], cbfResultToValue: CanBuildFrom[M[Result[A]], A, M[A]]): IO[M[A], E] =
Sequence(in, cbfIOToResult, cbfResultToValue)
val unit: IO[Unit, Effect] = fromTry(Success(()))
def zip[T, E1 <: Effect, S, E2 <: Effect](a: IO[T, E1], b: IO[S, E2]): IO[(T, S), E1 with E2] =
sequence(List(a, b)).map {
case a :: b :: Nil => (a.asInstanceOf[T], b.asInstanceOf[S])
case _ => fail("Sequence returned less than two elements")
def failed[T](exception: Throwable): IO[T, Effect] = fromTry(Failure(exception))
def successful[T](result: T): IO[T, Effect] = fromTry(Success(result))
def apply[T](body: => T): IO[T, Effect] = fromTry(Try(body))
def foldLeft[T, R, E <: Effect](ios: collection.immutable.Iterable[IO[T, E]])(zero: R)(op: (R, T) => R): IO[R, E] =
def reduceLeft[T, R >: T, E <: Effect](ios: collection.immutable.Iterable[IO[T, E]])(op: (R, T) => R): IO[R, E] =
def traverse[A, B, M[X] <: TraversableOnce[X], E <: Effect](in: M[A])(fn: A => IO[B, E])(implicit cbf: CanBuildFrom[M[A], B, M[B]]): IO[M[B], E] =
sequence( => cbf().++=(r).result)
trait IO[+T, -E <: Effect] {
def transactional: IO[T, E with Effect.Transaction] = Transactional(this)
def transformWith[S, E2 <: Effect](f: Try[T] => IO[S, E2]): IO[S, E with E2] =
TransformWith(this, f)
def transform[S](f: Try[T] => Try[S]): IO[S, E] =
transformWith { r =>
def lowerFromTry[U](implicit ev: T => Try[U]) =
def liftToTry: IO[Try[T], E] =
def failed: IO[Throwable, E] =
transform {
case Failure(t) => Success(t)
case Success(_) => Failure(new NoSuchElementException("IO.failed not completed with a throwable."))
def map[S](f: T => S): IO[S, E] = transform(
def flatMap[S, E2 <: Effect](f: T => IO[S, E2]): IO[S, E with E2] =
transformWith {
case Success(s) => f(s)
case f @ Failure(_) => IO.fromTry[S](f.asInstanceOf[Failure[S]]).asInstanceOf[IO[S, E with E2]]
def filter(p: T => Boolean): IO[T, E] =
map { r => if (p(r)) r else throw new NoSuchElementException("IO.filter predicate is not satisfied") }
final def withFilter(p: T => Boolean): IO[T, E] = filter(p)
def collect[S](pf: PartialFunction[T, S]): IO[S, E] =
map {
r => pf.applyOrElse(r, (t: T) => throw new NoSuchElementException("IO.collect partial function is not defined at: " + t))
def recover[U >: T](pf: PartialFunction[Throwable, U]): IO[U, E] =
transform { _ recover pf }
def recoverWith[U >: T, E2 <: Effect](pf: PartialFunction[Throwable, IO[U, E2]]): IO[U, E with E2] =
transformWith {
case Failure(t) => pf.applyOrElse(t, IO.failed _)
case s @ Success(_) => IO.fromTry(s)
def zip[S, E2 <: Effect](io: IO[S, E2]): IO[(T, S), E with E2] =, io)
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