Data.Registry.Internal.Cache

Cache for individual IO values when we wish to make singletons for database connection pools for example

This is inspired by https://hackage.haskell.org/package/io-memoize

Documentation

newtype Cache a

A thread-safe write-once cache. If you need more functionality, (e.g. multiple write, cache clearing) use an MVar instead.

Constructors

Cache (MVar (Maybe a))

Instances

Eq (Cache a)

Defined in Data.Registry.Internal.Cache

Methods

(==) :: Cache a -> Cache a -> Bool

(/=) :: Cache a -> Cache a -> Bool

fetch :: forall a m. MonadIO m => Cache a -> m a -> m a

Fetch the value stored in the cache, or call the supplied fallback and store the result, if the cache is empty.

newCache :: IO (Cache a)

Create an empty cache.