Data.Meep

A Map-like structure that contains up to one key-value pair

A Meep is strict in the key.

Meep k a is isomorphic to Maybe (k, a) with maybeing witnessing the isomorphism

Documentation

data Meep k a

A Meep from key k to value a

Instances

Bitraversable Meep

Biapply Meep

Bifunctor Meep

Bifoldable Meep

FunctorWithIndex k (Meep k)

FoldableWithIndex k (Meep k)

TraversableWithIndex k (Meep k)

Functor (Meep k)

Foldable (Meep k)

Traversable (Meep k)

(Eq k, Eq a) => Eq (Meep k a)

(Data k, Data a) => Data (Meep k a)

(Ord k, Ord a) => Ord (Meep k a)

(Show k, Show a) => Show (Meep k a)

Generic (Meep k a)

(Eq k, Semigroup a) => Semigroup (Meep k a)

Meeps intersection

Eq k => Ixed (Meep k a)

Eq k => At (Meep k a)

AsEmpty (Meep k a)

Typeable (* -> * -> *) Meep

type Rep (Meep k a)

type Index (Meep k a) = k

type IxValue (Meep k a) = a

empty :: Meep k a

O(1). An empty Meep

singleton :: k -> a -> Meep k a

O(1). A Meep with a single key-value pair

size :: Num b => Meep k a -> b

O(1). The size of the Meep

>>> size empty
0

>>> size (singleton 4 "foo")
1

null :: Meep k a -> Bool

O(1). The emptiness check for the Meep

>>> null empty
True

>>> null (singleton 4 "foo")
False

fromMaybe :: Maybe (k, a) -> Meep k a

O(1). Build the Meep

fromMaybe ≡ view (from maybeing)

toMaybe :: Meep k a -> Maybe (k, a)

O(1). Destroy the Meep

toMaybe ≡ view maybeing

maybeing :: Iso (Meep k v) (Meep k' v') (Maybe (k, v)) (Maybe (k', v'))

O(1). A witness to

Meep k v ≅ Maybe (k, v)

>>> singleton 4 "foo" ^. maybeing
Just (4,"foo")

>>> Nothing ^. from maybeing
fromMaybe Nothing

keys :: Meep k a -> Maybe k

O(1). Return all keys from the Meep

>>> keys (singleton 4 "foo")
Just 4

>>> keys empty
Nothing

elems :: Meep k a -> Maybe a

O(1). Return all values from the Meep

>>> elems (singleton 4 "foo")
Just "foo"

>>> elems empty
Nothing