Modulebarbies-2.1.1.0Haskell2010

Barbies.Constraints

Support for operating on Barbie-types with constrained functions.

Instance dictionaries

2 declarations

datadata Dict (c :: k -> Constraint) (a :: k) where

Dict c a is evidence that there exists an instance of c a.

It is essentially equivalent to Dict (c a) from the constraints package, but because of its kind, it allows us to define things like Dict Show.

Instances8GConstraints, Show1, Eq, Show, …

(ConstraintsB b, AllB c b) => GConstraints 0 c f (Other (b' (P 0 X)) (b X)) (Rec (b' (P 0 f)) (b f)) (Rec (b' (P 0 (Product (Dict c) f))) (b (Product (Dict c) f)))Defined in barbies-2.1.1.0 · Barbies.Internal.ConstraintsB · orphan
(ConstraintsB b, AllB c b) => GConstraints 0 c f (Self (b' (P 0 X)) (b X)) (Rec (b' (P 0 f)) (b f)) (Rec (b' (P 0 (Product (Dict c) f))) (b (Product (Dict c) f)))Defined in barbies-2.1.1.0 · Barbies.Internal.ConstraintsB · orphan
(ConstraintsT t, AllT c t) => GConstraints 1 c f (Other (t' (P 1 X) Y) (t X Y)) (Rec (t' (P 1 f) (P 0 y)) (t f y)) (Rec (t' (P 1 (Product (Dict c) f)) (P 0 y)) (t (Product (Dict c) f) y))Defined in barbies-2.1.1.0 · Barbies.Internal.ConstraintsT · orphan
(ConstraintsT t, AllT c t) => GConstraints 1 c f (Self (t' (P 1 X) Y) (t X Y)) (Rec (t' (P 1 f) (P 0 y)) (t f y)) (Rec (t' (P 1 (Product (Dict c) f)) (P 0 y)) (t (Product (Dict c) f) y))Defined in barbies-2.1.1.0 · Barbies.Internal.ConstraintsT · orphan
GConstraints n c f (Rec (P n X a') (X a)) (Rec (P n f a') (f a)) (Rec (P n (Product (Dict c) f) a') (Product (Dict c) f a))Defined in barbies-2.1.1.0 · Barbies.Generics.Constraints
Show1 (Dict c)Defined in barbies-2.1.1.0 · Barbies.Internal.Dicts
Eq (Dict c a)Defined in barbies-2.1.1.0 · Barbies.Internal.Dicts
Show (Dict c a)Defined in barbies-2.1.1.0 · Barbies.Internal.Dicts

valuerequiringDict :: (c a => r) -> Dict c a -> r

Turn a constrained-function into an unconstrained one that uses the packed instance dictionary instead.

3 declarations

typetype AllBF (c :: k -> Constraint) (f :: k1 -> k) (b :: (k1 -> Type) -> Type) = AllB (ClassF c f) b

Similar to AllB but will put the functor argument f between the constraint c and the type a. For example:

  AllB  Show   Person ~ (Show    String,  Show    Int)
  AllBF Show f Person ~ (Show (f String), Show (f Int))

classclass c (f a) => ClassF (c :: k -> Constraint) (f :: k1 -> k) (a :: k1)

ClassF has one universal instance that makes ClassF c f a equivalent to c (f a). However, we have

'ClassF c f :: k -> Constraint

This is useful since it allows to define constraint-constructors like ClassF Monoid Maybe

Instances1ClassF

classclass c (f a) (g a) => ClassFG (c :: k -> k1 -> Constraint) (f :: k2 -> k) (g :: k2 -> k1) (a :: k2)

Like ClassF but for binary relations.

Instances1ClassFG

c (f a) (g a) => ClassFG c f g aDefined in barbies-2.1.1.0 · Barbies.Internal.Dicts

1 declaration

classclass (c a, d a) => (&) (c :: k -> Constraint) (d :: k -> Constraint) (a :: k)

Instances1&

(c a, d a) => (&) c d aDefined in barbies-2.1.1.0 · Barbies.Internal.ConstraintsB