Moduleeffectful-core-2.7.1.2GHC2021

Effectful.Reader.Static

Support for access to a read only value of a particular type.

Note: strictly speaking the value is not read only because of local. If you want to ensure that the initial value never changes, use Effectful.Input.Static.

Contents

Effect
Handlers
Operations

Synopsis

data Reader
value runReader
value withReader
value ask
value asks
value local

Packageeffectful-core-2.7.1.2
Exports6
LanguageGHC2021
LicenceBSD-3-Clause
SourceStatic.hs

Effect

datadata Reader r (a :: Type -> Type) b

Source#

Provide access to a strict (WHNF), thread local, read only value of type r.

Instances2DispatchOf, StaticRep

type DispatchOf (Reader r) = 'Static 'NoSideEffectsDefined in effectful-core-2.7.1.2 · Effectful.Reader.Static
data StaticRep (Reader r)
- Reader r
Defined in effectful-core-2.7.1.2 · Effectful.Reader.Static

Handlers

valuerunReader

:: HasCallStack
=> r
The initial environment.
-> Eff (Reader r ': es) a
-> Eff es a

Source#

Run a Reader effect with the given initial environment.

valuewithReader

:: HasCallStack
=> (r1 -> r2)
The function to modify the environment.
-> Eff (Reader r2 ': es) a
Computation to run in the modified environment.
-> Eff (Reader r1 ': es) a

Source#

Execute a computation in a modified environment.

Operations

valueask :: (HasCallStack, Reader r :> es) => Eff es r

Source#

Fetch the value of the environment.

valueasks

:: (HasCallStack, Reader r :> es)
=> (r -> a)
The function to apply to the environment.
-> Eff es a

Source#

Retrieve a function of the current environment.

asks f ≡ f <$> ask

valuelocal

:: (HasCallStack, Reader r :> es)
=> (r -> r)
The function to modify the environment.
-> Eff es a
-> Eff es a

Source#

Execute a computation in a modified environment.

runReader r (local f m) ≡ runReader (f r) m