Polysemy.ScopedReader

This module provides a scoped-reader manner.

In contrast to a normal Reader effect, this manner makes connection of parameter type and effect explicit.

Example:

>>> import Polysemy ( interpret, runM, embed )
>>> import Polysemy.Output ( Output (Output), output, runOutputSem )

>>> :{
runDebug :: Member (Output String) r => String -> InterpreterFor (ScopedReader String (Output String)) r
runDebug = runScopedReader \i -> interpret \(Output o) -> output $ "[" <> i <> "] " <> o
:}

>>> :{
runM $ runOutputSem (embed . putStrLn) $ runDebug "root" do
    scopedReader $ output "test message 0"
    scopedLocal (<> ".scope-A") do
        scopedReader $ output "test message 1"
        scopedReader $ output "test message 2"
        scopedLocal (<> ".scope-B") do
            scopedReader $ output "test message 3"
:}
[root] test message 0
[root.scope-A] test message 1
[root.scope-A] test message 2
[root.scope-A.scope-B] test message 3

Documentation

scopedLocal :: forall i p resource effect r. Member (ScopedReader i effect) r => (i -> i) -> InterpreterFor (ScopedFix i effect) r

scopedReader :: Member (ScopedReader i effect) r => Sem (effect ': r) a -> Sem r a

type ScopedReader i effect = ScopedFix i effect

runScopedReader :: (i -> InterpreterFor effect r) -> i -> Sem (ScopedReader i effect ': r) a -> Sem r a

data ScopedFixP p resource effect m a where

Constructors

ScopedEffect :: effect m a -> ScopedFixP p resource effect m a

ScopedFix :: ScopedP p resource (ScopedFixP p resource effect) m a -> ScopedFixP p resource effect m a

type ScopedFix = ScopedFixP ()

scopedEffect :: Member (ScopedFixP p resource effect) r => Sem (effect ': r) a -> Sem r a

scopedFix :: Member (ScopedFixP p resource effect) r => Sem (ScopedP p resource (ScopedFixP p resource effect) ': r) a -> Sem r a