Moduleeffectful-core-2.3.0.1Haskell2010

Effectful.Internal.Effect

Type-safe indexing for Effectful.Internal.Monad.Env.

This module is intended for internal use only, and may change without warning in subsequent releases.

2 types
4 classes

Packageeffectful-core-2.3.0.1
Exports7
LanguageHaskell2010
LicenceBSD-3-Clause
SourceEffect.hs

typetype Effect = (Type -> Type) -> Type -> Type

The kind of effects.

classclass (:>) (e :: Effect) (es :: [Effect]) where

A constraint that requires that a particular effect e is a member of the type-level list es. This is used to parameterize an Eff computation over an arbitrary list of effects, so long as e is somewhere in the list.

For example, a computation that only needs access to a mutable value of type Integer would have the following type:

State Integer :> es => Eff es ()

Methods

reifyIndex :: Int
Get the position of e in es.
Note: GHC is kind enough to cache these values as they're top level CAFs, so the lookup is amortized O(1) without any language level tricks.

Instances3:>

TypeError (('Text "There is no handler for '" ':<>: 'ShowType e) ':<>: 'Text "' in the context") => e :> '[]Defined in effectful-core-2.3.0.1 · Effectful.Internal.Effect
e :> (e ': es)Defined in effectful-core-2.3.0.1 · Effectful.Internal.Effect
e :> es => e :> (x ': es)Defined in effectful-core-2.3.0.1 · Effectful.Internal.Effect

familytype family (:>>) (xs :: [Effect]) (es :: [Effect]) :: Constraint where

Deprecated. Usage of (:>>) slows down GHC too much, so it will be removed in 3.0.0.0. See https://github.com/haskell-effectful/effectful/issues/52#issuecomment-1269155485 for more information.

Convenience operator for expressing that a function uses multiple effects in a more concise way than enumerating them all with (:>).

[E1, E2, ..., En] :>> es ≡ (E1 :> es, E2 :> es, ..., En :> es)

Equations

(:>>) '[] es = ()
(:>>) (x ': xs) es = (x :> es, xs :>> es)

classclass KnownPrefix es => Subset (xs :: [Effect]) (es :: [Effect]) where

Provide evidence that xs is a subset of es.

Methods

subsetFullyKnown :: Bool
reifyIndices :: [Int]

Instances3Subset

(KnownPrefix es, IsUnknownSuffixOf xs es) => Subset xs esDefined in effectful-core-2.3.0.1 · Effectful.Internal.Effect
KnownPrefix es => Subset '[] esDefined in effectful-core-2.3.0.1 · Effectful.Internal.Effect
(e :> es, Subset xs es) => Subset (e ': xs) esDefined in effectful-core-2.3.0.1 · Effectful.Internal.Effect

classclass KnownPrefix (es :: [Effect]) where

Calculate length of a statically known prefix of es.

Methods

prefixLength :: Int

Instances2KnownPrefix

KnownPrefix esDefined in effectful-core-2.3.0.1 · Effectful.Internal.Effect
KnownPrefix es => KnownPrefix (e ': es)Defined in effectful-core-2.3.0.1 · Effectful.Internal.Effect

classclass IsUnknownSuffixOf (xs :: [Effect]) (es :: [Effect])

Require that xs is the unknown suffix of es.

Instances2IsUnknownSuffixOf

xs ~ es => IsUnknownSuffixOf xs esDefined in effectful-core-2.3.0.1 · Effectful.Internal.Effect
IsUnknownSuffixOf xs es => IsUnknownSuffixOf xs (e ': es)Defined in effectful-core-2.3.0.1 · Effectful.Internal.Effect

Re-exports

1 declaration

typetype Type = TYPE LiftedRep

The kind of types with lifted values. For example Int :: Type.