Data.Registry.Internal.Cache

Cache for individual IO values when we wish to memoize actions 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 (Map Key a))

Instances

Eq (Cache a)

Defined in Data.Registry.Internal.Cache

Methods

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

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

type Key = Maybe [SpecializationPath]

We need to cache different values to account for the fact that different values might be specialized for the same type

fetch :: forall a m. (MonadIO m, Typeable a) => Cache a -> Key -> 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.