effectful-data-cache

import Effectful
import Effectful.Cache
import Prelude hiding (lookup)

main :: IO ()
main = runEff . runCache Nothing $ do
  insert "key" (42 :: Int)
  v <- lookup @String @Int "key"
  liftIO $ print v

runCache creates a fresh store; runCacheWith wraps an existing Data.Cache.Cache so it can be shared with non-effectful code.

Tracing

traceCache wraps every operation in an OpenTelemetry span (cache.insert, cache.lookup, …), with cache.hit on lookups and cache.size on size/keys. Keys and values are never recorded.

import Effectful.Cache.OpenTelemetry (traceCache)

main = runEff . runCache Nothing . traceCache tracer $ do
  insert "key" (42 :: Int)

It is an interposer, so it layers over any interpreter and can be omitted without touching call sites.