stamina.hs/README.md

Stamina.hs

WIP: doesn't work yet, in design phase.

A retry Haskell library for humans:

• Exponential backoff with jitter between retries.
• Limit the number of retries and total time.
• Stamina.HTTP for retrying retriable HTTP Exceptions
• Introspectable retry state for logging

Design goals

• Defaults that make sense most of the time.
• Simple interface.
• Documented.

API

defaultRetrySettings :: RetrySettings

-- Retry on all sync exceptions
retry :: MonadIO m => RetrySettings -> (RetryStatus -> m a) -> m a

-- Retry on specific exceptions
retryOnExceptions :: (Exception e, MonadIO m) => RetrySettings -> [Handler RetryAction] -> (RetryStatus -> m a) -> m a

data RetryAction = Skip | Retry | RetryAfter Int

Example

import qualified Stamina

main :: IO ()
main = do
    Stamina.retry Stamina.defaultRetrySettings $ \retryStatus -> do
        ... monadic logic that raises exceptions

Development

1. Install devenv.sh.

2. devenv shell

3. stack build

Credits

• Heavily inspired by stamina for Python.
• retry as case study for what needs to be supported