Data.HSet

Documentation

data HSet elems where

Heterogeneous set (list) of elements with unique types. Usefull with MonadReader.

>>> let x = HSCons (10 :: Int) $ HSCons (20 :: Double) HSNil
>>> x
HSCons (10) (HSCons (20.0) (HSNil))

>>> hget x :: Int
10

>>> hget x :: Double
20.0

Note how hget just takes specific element from list of uniqly typed elements depending on what type is required to be returned.

Constructors

HSNil :: HSet []

HSCons :: (False ~ Elem elem elems) => !elem -> !(HSet elems) -> HSet (elem : elems)

Instances

(Eq e, Eq (HSet els)) => Eq (HSet ((:) * e els))

Eq (HSet ([] *))

(Ord e, Ord (HSet els)) => Ord (HSet ((:) * e els))

Ord (HSet ([] *))

(Show e, Show (HSet els)) => Show (HSet ((:) * e els))

Show (HSet ([] *))

Typeable ([*] -> *) HSet

class (i ~ Index e els) => HGet els e i where

Typeclass for sets and elements.

Methods

hget :: HSet els -> e

Get any data from HSet for you

Instances

HGet ((:) * e els) e Z

((~) Nat i (Index * e els), (~) Nat (S i) (Index * e ((:) * e1 els)), HGet els e i) => HGet ((:) * e1 els) e (S i)

type Contains els e = HGet els e (Index e els)

Helper typefamily to derive that second argument contained in list of first argument and we can perform hget from set.

hask :: (MonadReader (HSet els) m, Contains els e) => m e

Work with Labeled elements

hgetLabeled :: forall proxy label e els. Contains els (Labeled label e) => proxy label -> HSet els -> e

>>> let y = HSCons (Labeled 10 :: Labeled "x" Int) $ HSCons (Labeled 20 :: Labeled "y" Int) HSNil
>>> y
HSCons (Labeled {unLabeled = 10}) (HSCons (Labeled {unLabeled = 20}) (HSNil))

>>> hgetLabeled (Proxy :: Proxy "x") y :: Int
10

>>> hgetLabeled (Proxy :: Proxy "y") y :: Int
20

haskLabeled :: forall proxy label e els m. (Contains els (Labeled label e), MonadReader (HSet els) m, Applicative m) => proxy label -> m e

Reexports

module Data.HSet.Labeled