Data.TypeMap.Dynamic

Dynamic type maps

data TypeMap x

Map from types t of kind * to values of type Item x t.

type family Item x t

An extensible type family mapping types (as keys) to types of values, parameterized by types x.

Instances

type Item (OfType a) t

Defined in Data.TypeMap.Internal.Dynamic

type Item (OfType a) t = a

Basic operations

empty :: TypeMap x

Empty type map.

null :: TypeMap x -> Bool

Whether the map is empty.

size :: TypeMap x -> Int

The number of elements in the map.

insert :: forall t x proxy. Typeable t => proxy t -> Item x t -> TypeMap x -> TypeMap x

Insert an element indexed by type t.

(<:) :: forall t x proxy. Typeable t => TypeMap x -> (proxy t, Item x t) -> TypeMap x

Infix version of insert to facilitate a literal-ish syntax:

empty
  <: (Proxy k1, v1)
  <: (Proxy k2, v2)

update :: forall t x proxy. Typeable t => proxy t -> (Item x t -> Maybe (Item x t)) -> TypeMap x -> TypeMap x

Update an element indexed by type t.

alter :: forall t x proxy. Typeable t => proxy t -> (Maybe (Item x t) -> Maybe (Item x t)) -> TypeMap x -> TypeMap x

Update a (possibly absent) element indexed by type t.

lookup :: forall t x proxy. Typeable t => proxy t -> TypeMap x -> Maybe (Item x t)

Lookup an element indexed by type t.

delete :: forall t x proxy. Typeable t => proxy t -> TypeMap x -> TypeMap x

Delete a key and its value from the map. Does nothing if the key does not exist.

Traversals and folds

map :: forall x y. (forall t. Typeable t => Proxy t -> Item x t -> Item y t) -> TypeMap x -> TypeMap y

Map a function on all elements.

traverse :: forall f x y. Applicative f => (forall t. Typeable t => Proxy t -> Item x t -> f (Item y t)) -> TypeMap x -> f (TypeMap y)

Traverse the type map. (map with effects.)

toList :: forall r. TypeMap (OfType r) -> [r]

Reduce a constant type map into a plain list of values.

toListMap :: forall tm r. (forall t. Proxy t -> Item tm t -> r) -> TypeMap tm -> [r]

Collapse a type map into a plain list of values.

Set-like operations

union :: forall x. TypeMap x -> TypeMap x -> TypeMap x

Left-biased union of two maps; it keeps the first key if duplicates are found.

difference :: forall x. TypeMap x -> TypeMap x -> TypeMap x

Difference of two maps; keep elements of the first map which are not in the second.

intersection :: forall x y. TypeMap x -> TypeMap y -> TypeMap x

Intersection of two maps; keep elements of the first map which are also in the second.

Type-level mappings

data OfType a

A constant mapping to type a. TypeMap (OfType a) is the type of maps from types to values of type a.

Instances

type UnTyped (OfType a)

Defined in Data.TypeMap.Internal.Dynamic

type UnTyped (OfType a) = a

type Typed (OfType a) t

Defined in Data.TypeMap.Internal.Dynamic

type Typed (OfType a) t = a

type Item (OfType a) t

Defined in Data.TypeMap.Internal.Dynamic

type Item (OfType a) t = a