Name: slick-cats
Owner: Scala Language-Integrated Connection Kit
Description: Cats instances for Slick DBIO
Forked from: RMSone/slick-cats
Created: 2016-12-03 22:21:57.0
Updated: 2016-12-03 22:34:09.0
Pushed: 2016-12-03 17:26:47.0
Homepage: null
Size: 27
Language: Scala
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Cats instances for Slick's DBIO including:
SlickCats is not yet published but can be used by publishing locally via sbt publishLocal and then adding
the following to your build definition:
aryDependencies += "com.rms.miu" %% "slick-cats" % version
Because of possible binary incompatibilities here are the dependency versions used in each release
| slick-cats version | slick version | cats version | |:——————:|:————-:|:————:| | 0.1 | 3.1.1 | 0.5.0 | | 0.2 | 3.1.1 | 0.6.0 | | 0.3 | 3.1.1 | 0.7.0 |
Some or all of the following imports may be needed:
rt cats._
rt cats.implicits._
rt slick.dbio._
rt com.rms.miu.slickcats.DBIOInstances._
Additionally, be sure to have an implicit ExecutionContext in scope. The implicit conversions require it
and will fail with non obvious errors if it's missing.
a> implicitly[Monad[DBIO]]
sole>:25: error: could not find implicit value for parameter e: cats.Monad[slick.dbio.DBIO]
implicitly[Monad[DBIO]]
^
cala
rt scala.concurrent.ExecutionContext.Implicits.global
instances will be available for:
icitly[Monad[DBIO]]
icitly[MonadError[DBIO, Throwable]]
icitly[CoflatMap[DBIO]]
icitly[Functor[DBIO]]
icitly[Applicative[DBIO]]
If a Monoid exists for A, here taken as Int, then the following is also available
icitly[Group[DBIO[Int]]]
icitly[Semigroup[DBIO[Int]]]
icitly[Monoid[DBIO[Int]]]
Instances are supplied for DBIO[A] only. Despite being the same thing,
type aliases will not match for implicit conversion. This means that the following
a> def monad[F[_] : Monad, A](fa: F[A]): F[A] = fa
d: [F[_], A](fa: F[A])(implicit evidence$1: cats.Monad[F])F[A]
a> val fail1: DBIOAction[String, NoStream, Effect.All] = DBIO.successful("hello")
1: slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect.All] = SuccessAction(hello)
a> val fail2 = DBIO.successful("hello")
2: slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect] = SuccessAction(hello)
a> val success: DBIO[String] = DBIO.successful("hello")
ess: slick.dbio.DBIO[String] = SuccessAction(hello)
will not compile
a> monad(fail1)
sole>:28: error: no type parameters for method monad: (fa: F[A])(implicit evidence$1: cats.Monad[F])F[A] exist so that it can be applied to arguments (slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect.All])
because ---
ment expression's type is not compatible with formal parameter type;
nd : slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect.All]
uired: ?F[?A]
monad(fail1)
^
sole>:28: error: type mismatch;
nd : slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect.All]
uired: F[A]
monad(fail1)
^
a> monad(fail2)
sole>:28: error: no type parameters for method monad: (fa: F[A])(implicit evidence$1: cats.Monad[F])F[A] exist so that it can be applied to arguments (slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect])
because ---
ment expression's type is not compatible with formal parameter type;
nd : slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect]
uired: ?F[?A]
monad(fail2)
^
sole>:28: error: type mismatch;
nd : slick.dbio.DBIOAction[String,slick.dbio.NoStream,slick.dbio.Effect]
uired: F[A]
monad(fail2)
^
but
a> monad(success)
1: slick.dbio.DBIO[String] = SuccessAction(hello)
will compile fine.
This README is compiled using tut to ensure that only working examples are given.
Feedback of any kind is appreciated. Especially if you have any ideas on getting around the DBIOAction issue above.