Bind
Resource
data constructor that encodes the flatMap
operation.
Type members
Inherited types
Value members
Inherited methods
Given a Resource
, possibly built by composing multiple
Resource
s monadically, returns the acquired resource, as well
as an action that runs all the finalizers for releasing it.
Given a Resource
, possibly built by composing multiple
Resource
s monadically, returns the acquired resource, as well
as an action that runs all the finalizers for releasing it.
If the outer F
fails or is interrupted, allocated
guarantees
that the finalizers will be called. However, if the outer F
succeeds, it's up to the user to ensure the returned F[Unit]
is called once A
needs to be released. If the returned
F[Unit]
is not called, the finalizers will not be run.
For this reason, this is an advanced and potentially unsafe api
which can cause a resource leak if not used correctly, please
prefer use as the standard way of running a Resource
program.
Use cases include interacting with side-effectful apis that
expect separate acquire and release actions (like the before
and after
methods of many test frameworks), or complex library
code that needs to modify or move the finalizer for an existing
resource.
- Inherited from
- ResourceLike
Combines two Resource
instances by lifting the behaviour of a
SemigroupK
instance into the resource context
Combines two Resource
instances by lifting the behaviour of a
SemigroupK
instance into the resource context
- Inherited from
- Resource
Applies an effectful transformation to the allocated resource. Like a
flatMap
on F[A]
while maintaining the resource context
Applies an effectful transformation to the allocated resource. Like a
flatMap
on F[A]
while maintaining the resource context
- Inherited from
- ResourceLike
Applies an effectful transformation to the allocated resource. Like a
flatTap
on F[A]
while maintaining the resource context
Applies an effectful transformation to the allocated resource. Like a
flatTap
on F[A]
while maintaining the resource context
- Inherited from
- ResourceLike
Implementation for the flatMap
operation, as described via the
cats.Monad
type class.
Implementation for the flatMap
operation, as described via the
cats.Monad
type class.
- Inherited from
- ResourceLike
Given a mapping function, transforms the resource provided by this Resource.
Given a mapping function, transforms the resource provided by this Resource.
This is the standard Functor.map
.
- Inherited from
- ResourceLike
Given a natural transformation from F
to G
, transforms this
Resource from effect F
to effect G
.
Given a natural transformation from F
to G
, transforms this
Resource from effect F
to effect G
.
- Inherited from
- Resource
Runs finalizer
when this resource is closed. Unlike the release action passed to Resource.make
, this will
run even if resource acquisition fails or is canceled.
Runs finalizer
when this resource is closed. Unlike the release action passed to Resource.make
, this will
run even if resource acquisition fails or is canceled.
- Inherited from
- Resource
Like onFinalize
, but the action performed depends on the exit case.
Like onFinalize
, but the action performed depends on the exit case.
- Inherited from
- Resource
Allocates two resources concurrently, and combines their results in a tuple.
Allocates two resources concurrently, and combines their results in a tuple.
The finalizers for the two resources are also run concurrently with each other, but within each of the two resources, nested finalizers are run in the usual reverse order of acquisition.
Note that Resource
also comes with a cats.Parallel
instance
that offers more convenient access to the same functionality as
parZip
, for example via parMapN
:
def mkResource(name: String) = {
val acquire =
IO(scala.util.Random.nextInt(1000).millis).flatMap(IO.sleep) *>
IO(println(s"Acquiring $$name")).as(name)
val release = IO(println(s"Releasing $$name"))
Resource.make(acquire)(release)
}
val r = (mkResource("one"), mkResource("two"))
.parMapN((s1, s2) => s"I have $s1 and $s2")
.use(msg => IO(println(msg)))
- Inherited from
- ResourceLike
Allocates a resource and supplies it to the given function.
The resource is released as soon as the resulting F[B]
is
completed, whether normally or as a raised error.
Allocates a resource and supplies it to the given function.
The resource is released as soon as the resulting F[B]
is
completed, whether normally or as a raised error.
- Value Params
- f
the function to apply to the allocated resource
- Returns
the result of applying [F] to
- Inherited from
- ResourceLike