Data.Constraint.Forall

constraints-0.14.2: Constraint manipulation

Copyright | (C) 2011-2021 Edward Kmett (C) 2015 Ørjan Johansen (C) 2016 David Feuer
License | BSD-style (see the file LICENSE)
Maintainer | Edward Kmett <ekmett@gmail.com>
Stability | experimental
Portability | non-portable
Safe Haskell | Trustworthy
Language | Haskell2010

Data.Constraint.Forall

Description

This module uses a trick to provide quantification over constraints.

Synopsis

- class (forall (a :: k). p a) => Forall (p :: k -> Constraint)
- inst :: forall {k} p (a :: k). Forall p :- p a
- class Forall (ComposeC p f) => ForallF (p :: k2 -> Constraint) (f :: k1 -> k2)
- instF :: forall {k2} {k1} p (f :: k1 -> k2) (a :: k1). ForallF p f :- p (f a)
- type Forall1 (p :: k -> Constraint) = Forall p
- inst1 :: forall p (f :: Type -> Type). Forall p :- p f
- class Forall (Q p t) => ForallT (p :: k4 -> Constraint) (t :: (k1 -> k2) -> k3 -> k4)
- instT :: forall k1 k2 k3 k4 p (t :: (k1 -> k2) -> k3 -> k4) (f :: k1 -> k2) (a :: k3). ForallT p t :- p (t f a)
- type family ForallV :: k -> Constraint
- class InstV (p :: k) c | k c -> p where
  - instV :: ForallV p :- c
- forall_ :: (forall (a :: k). Dict (p a)) -> Dict (Forall p)

# Documentation

class (forall (a :: k). p a) => Forall (p :: k -> Constraint) #

#### Instances

Instances details

(forall (a :: k). p a) => Forall (p :: k -> Constraint) # |
Instance details Defined in Data.Constraint.Forall

inst :: forall {k} p (a :: k). Forall p :- p a #

Instantiate a quantified ``Forall` p` constraint at type `a`.

class Forall (ComposeC p f) => ForallF (p :: k2 -> Constraint) (f :: k1 -> k2) #

A representation of the quantified constraint `forall a. p (f a)`.

#### Instances

Instances details

Forall (ComposeC p f) => ForallF (p :: k2 -> Constraint) (f :: k1 -> k2) # |
Instance details Defined in Data.Constraint.Forall

instF :: forall {k2} {k1} p (f :: k1 -> k2) (a :: k1). ForallF p f :- p (f a) #

Instantiate a quantified ``ForallF` p f` constraint at type `a`.

type Forall1 (p :: k -> Constraint) = Forall p #

inst1 :: forall p (f :: Type -> Type). Forall p :- p f #

Instantiate a quantified constraint on kind `* -> *`. This is now redundant since ``inst`` became polykinded.

class Forall (Q p t) => ForallT (p :: k4 -> Constraint) (t :: (k1 -> k2) -> k3 -> k4) #

A representation of the quantified constraint `forall f a. p (t f a)`.

#### Instances

Instances details

Forall (Q p t) => ForallT (p :: k4 -> Constraint) (t :: (k1 -> k2) -> k3 -> k4) # |
Instance details Defined in Data.Constraint.Forall

instT :: forall k1 k2 k3 k4 p (t :: (k1 -> k2) -> k3 -> k4) (f :: k1 -> k2) (a :: k3). ForallT p t :- p (t f a) #

Instantiate a quantified ``ForallT` p t` constraint at types `f` and `a`.

type family ForallV :: k -> Constraint #

A representation of the quantified constraint `forall a1 a2 ... an . p a1 a2 ... an`, supporting a variable number of parameters.

#### Instances

Instances details

type ForallV # |
Instance details Defined in Data.Constraint.Forall type ForallV

class InstV (p :: k) c | k c -> p where #

Instantiate a quantified ``ForallV` p` constraint as `c`, where `c ~ p a1 a2 ... an`.

Methods

instV :: ForallV p :- c #

#### Instances

Instances details

p ~ c => InstV (p :: Constraint) c # |
Instance details Defined in Data.Constraint.Forall Methods instV :: ForallV p :- c #
p a ~ c => InstV (p :: k -> Constraint) c # |
Instance details Defined in Data.Constraint.Forall Methods instV :: ForallV p :- c #
InstV (p a) c => InstV (p :: k1 -> k2 -> k3) c # |
Instance details Defined in Data.Constraint.Forall Methods instV :: ForallV p :- c #

forall_ :: (forall (a :: k). Dict (p a)) -> Dict (Forall p) #