Music.Time.Meta

Provides a way to annotate data-types with Transformable meta-data. Inspired by Clojure meta-data and Diagrams styles.

Attributes

type AttributeClass a = (Typeable a, Monoid a, Semigroup a)

Class of values that can be wrapped.

type TAttributeClass a = (Transformable a, AttributeClass a)

Class of values that can be wrapped and transformed.

data Attribute :: *

An existential wrapper type to hold attributes.

Instances

Semigroup Attribute

Transformable Attribute

Splittable Attribute

Reversible Attribute

Creating attributes

wrapAttr :: AttributeClass a => a -> Attribute

Wrap up an attribute.

wrapTAttr :: TAttributeClass a => a -> Attribute

Wrap up a transformable attribute.

unwrapAttr :: AttributeClass a => Attribute -> Maybe a

Convert something from an attribute. Also works with transformable attributes

Meta-data

data Meta

Instances

Show Meta

Monoid Meta

The empty meta contains no attributes; composition of metas is a union of attributes; if the two metas have attributes of the same type they are combined according to their semigroup structure.

Semigroup Meta

Transformable Meta

Splittable Meta

Reversible Meta

HasMeta Meta

Creating meta-data

wrapMeta :: forall a. AttributeClass a => a -> Meta

Convert something from meta-data. Also works with transformable attributes

wrapTMeta :: forall a. TAttributeClass a => a -> Meta

Convert something to meta-data.

unwrapMeta :: forall a. AttributeClass a => Meta -> Maybe a

Convert something from meta-data.

The HasMeta class

class HasMeta a where

Type class for things which have meta-data.

Methods

meta :: Lens' a Meta

Access the meta-data.

Instances

HasMeta Meta

HasMeta a => HasMeta (Maybe a)

HasMeta (AddMeta a)

HasMeta (Score a)

HasMeta a => HasMeta (b, a)

HasMeta a => HasMeta (Twain b a)

getMeta :: HasMeta a => a -> Meta

Extract meta-data.

mapMeta :: HasMeta a => (Meta -> Meta) -> a -> a

Map over meta-data.

setMeta :: HasMeta a => Meta -> a -> a

Update meta-data.

applyMeta :: HasMeta a => Meta -> a -> a

Apply meta-information by combining it with existing meta-information.

setMetaAttr :: (AttributeClass b, HasMeta a) => b -> a -> a

Update a meta attribute.

setMetaTAttr :: (TAttributeClass b, HasMeta a) => b -> a -> a

Update a meta attribute.

preserveMeta :: (HasMeta a, HasMeta b) => (a -> b) -> a -> b

Apply a function without affecting meta-data.

Add meta-data to arbitrary types

data AddMeta a

Annotate an arbitrary type with meta-data, preserving instances of all common type classes. In particular Functor and Applicative is lifted and Compose AddMeta is semantically equivalent to Identity.

Instances

Monad AddMeta

Functor AddMeta

Applicative AddMeta

Foldable AddMeta

Comonad AddMeta

Bounded a => Bounded (AddMeta a)

Enum a => Enum (AddMeta a)

Eq a => Eq (AddMeta a)

Floating a => Floating (AddMeta a)

Fractional a => Fractional (AddMeta a)

Integral a => Integral (AddMeta a)

Num a => Num (AddMeta a)

Ord a => Ord (AddMeta a)

Real a => Real (AddMeta a)

RealFrac a => RealFrac (AddMeta a)

Show a => Show (AddMeta a)

Monoid a => Monoid (AddMeta a)

Semigroup a => Semigroup (AddMeta a)

Wrapped (AddMeta a)

Transformable a => Transformable (AddMeta a)

HasDuration a => HasDuration (AddMeta a)

HasPosition a => HasPosition (AddMeta a)

Splittable a => Splittable (AddMeta a)

Reversible a => Reversible (AddMeta a)

HasMeta (AddMeta a)

Rewrapped (AddMeta a) (AddMeta b)

Typeable (* -> *) AddMeta

type Unwrapped (AddMeta a) = Twain Meta a

annotated :: Lens (AddMeta a) (AddMeta b) a b

Access the annotated value.

over annotated = fmap

unannotated :: Getter a (AddMeta a)

Access the annotated value.

view fromAnnotated = pure

unsafeAnnotated :: Iso (AddMeta a) (AddMeta b) a b

Access the annotated value. This is only an isomorphism up to meta-data equivalence. In particular under unsafeAnnotated leads to meta-data being thrown away. See annotated and unannotated for safe (but less general) definitions.

over annotated = fmap