Copyright	(c) Hans Hoglund 2012–2014
License	BSD-style
Maintainer	hans@hanshoglund.se
Stability	experimental
Portability	non-portable (TF,GNTD)
Safe Haskell	None
Language	Haskell2010

Music.Time.Meta

Contents

Attributes
- Creating attributes
Meta-data

Description

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

Synopsis

Attributes

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

Class of values that can be wrapped.

type TAttributeClass a = (Transformable a, AttributeClass a) Source

Class of values that can be wrapped and transformed.

data Attribute :: * Source

An existential wrapper type to hold attributes.

Instances

Semigroup Attribute
Transformable Attribute
Reversible Attribute

Creating attributes

wrapAttr :: AttributeClass a => a -> Attribute Source

Wrap up an attribute.

wrapTAttr :: TAttributeClass a => a -> Attribute Source

Wrap up a transformable attribute.

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

Convert something from an attribute. Also works with transformable attributes

Meta-data

data Meta Source

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
Reversible Meta
HasMeta Meta

Creating meta-data

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

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

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

Convert something to meta-data.

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

Convert something from meta-data.

The HasMeta class

class HasMeta a where Source

Type class for things which have meta-data.

Methods

meta :: Lens' a Meta Source

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 Source

Extract meta-data.

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

Map over meta-data.

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

Update meta-data.

metaTypes :: HasMeta a => a -> [String] Source

Show the types of meta-data attachd to this value. Useful for debugging.

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

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

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

Update a meta attribute.

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

Update a meta attribute.

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

Apply a function without affecting meta-data.

Add meta-data to arbitrary types

data AddMeta a Source

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
Traversable 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)
Wrapped (AddMeta a)
Semigroup a => Semigroup (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 Source

Access the annotated value.

over annotated = fmap

unannotated :: Getter a (AddMeta a) Source

Access the annotated value.

view fromAnnotated = pure

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

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