Coeval

Promotes a non-strict value to a Coeval.

Alias of eval.

Promote a non-strict value representing a Coeval to a Coeval of the same type.

Alias for eval.

Promote a non-strict value to a Coeval, catching exceptions in the process.

Note that since Coeval is not memoized, this will recompute the value each time the Coeval is executed.

Promote a non-strict value to a Coeval that is memoized on the first evaluation, the result being then available on subsequent evaluations.

Guarantees thread-safe idempotency.

'''UNSAFE''' — this operation allocates a shared, mutable reference, which can break in certain cases referential transparency, even if this operation guarantees idempotency (i.e. referential transparency implies idempotency, but idempotency does not imply referential transparency).

   The allocation of a mutable reference is known to be a
   side effect, thus breaking referential transparency,
   even if calling this method does not trigger the evaluation
   of side effects suspended by the source.

   Use with care. Sometimes it's easier to just keep a shared,
   memoized reference to some connection, but keep in mind
   it might be better to pass such a reference around as
   a parameter.

Converts any value that has a CoevalLike instance into a Coeval.

Converts a Scala Either into a Coeval.

Value parameters:

f: is a function that knows how to convert into a Throwable in order to throw that error in the MonadError context.

Converts a Scala Try into a Coeval.

Builds a Coeval of Left

Returns a F ~> Coeval (FunctionK) for transforming any supported data-type into Coeval.

Useful for mapK transformations, for example when working with Resource or Iterant:

 import cats.effect._
 import monix.eval._
 import java.io._

 def open(file: File) =
   Resource[SyncIO, InputStream](SyncIO {
     val in = new FileInputStream(file)
     (in, SyncIO(in.close()))
   })

 // Lifting to a Resource of Coeval
 val res: Resource[Coeval, InputStream] =
   open(new File("sample")).mapK(Coeval.liftFrom[SyncIO])

See cats.arrow.FunctionK.

Generates Coeval ~> F (FunctionK) values for converting from Coeval to supporting types (for which we have a CoevalLift instance).

See the documentation.

 import cats.effect._
 import monix.eval._
 import java.io._

 def open(file: File) =
   Resource[Coeval, InputStream](Coeval {
     val in = new FileInputStream(file)
     (in, Coeval(in.close()))
   })

 // Lifting to a Resource of Task
 val res: Resource[Task, InputStream] =
   open(new File("sample")).mapK(Coeval.liftTo[Task])

 // This was needed in order to process the resource
 // with a Task, instead of a Coeval
 res.use { in =>
   Task {
     in.read()
   }
 }

Generates Coeval ~> F function values (FunctionK) for converting from Coeval to types for which we have a cats.effect.Sync instance.

See also:: cats.arrow.FunctionK

cats.effect.Sync Prefer to use liftTo, this alternative is provided in order to force the usage of cats.effect.Sync, since CoevalLift is lawless.

Pairs 2 Coeval values, applying the given mapping function.