Modulepolysemy-1.9.2.0Haskell2010

Polysemy.Tagged

1 type
4 values

Packagepolysemy-1.9.2.0
Exports5
LanguageHaskell2010
LicenceBSD-3-Clause
SourceTagged.hs

Effect

1 declaration

newtypenewtype Tagged (k3 :: k) (e :: k1 -> k2 -> Type) (m :: k1) (a :: k2) where

An effect for annotating effects and disambiguating identical effects.

Constructors

Tagged :: e m a -> Tagged k3 e m a

Actions

2 declarations

valuetag :: Member (Tagged k2 e) r => Sem (e ': r) a -> Sem r a

Tag uses of an effect, effectively gaining access to the tagged effect locally.

This may be used to create tagged- variants of regular actions.

For example:

taggedLocal :: forall k i r a
             . Member (Tagged k (Reader i)) r
            => (i -> i)
            -> Sem r a
            -> Sem r a
taggedLocal f m =
  tag @k @(Reader i) $ local @i f (raise m)

valuetagged :: Sem (e ': r) a -> Sem (Tagged k2 e ': r) a

A reinterpreting version of tag.

Interpretations

2 declarations

valueuntag :: Sem (Tagged k2 e ': r) a -> Sem (e ': r) a

Run a Tagged k e effect through reinterpreting it to e

valueretag :: Member (Tagged k4 e) r => Sem (Tagged k3 e ': r) a -> Sem r a

Transform a Tagged k1 e effect into a Tagged k2 e effect