STMContainers.Multimap

Documentation

data Multimap k v

A multimap, based on an STM-specialized hash array mapped trie.

Basically it's just a wrapper API around Map k (Set v).

type Association k v = (Eq k, Hashable k, Eq v, Hashable v)

A standard constraint for items.

new :: STM (Multimap k v)

Construct a new multimap.

insert :: Association k v => v -> k -> Multimap k v -> STM ()

Insert an item.

delete :: Association k v => v -> k -> Multimap k v -> STM ()

Delete an item by a value and a key.

lookup :: Association k v => v -> k -> Multimap k v -> STM Bool

Look up an item by a value and a key.

focus :: Association k v => StrategyM STM () r -> v -> k -> Multimap k v -> STM r

Focus on an item with a strategy by a value and a key.

This function allows to perform simultaneous lookup and modification.

The strategy is over a unit since we already know, which value we're focusing on and it doesn't make sense to replace it, however we still can still decide wether to keep or remove it.

foldM :: (a -> (k, v) -> STM a) -> a -> Multimap k v -> STM a

Fold all the items.

null :: Multimap k v -> STM Bool

Check on being empty.