Apache-2.0 licensed by Domen Kožar
Maintained by [email protected]
This version can be pinned in stack with:stamina-0.1.0.3@sha256:7a41ce24449fdabb1ca8ef88fb46b5a6bb1c90a0da9017e92790f1397034217e,1349

Module documentation for 0.1.0.3

Used by 1 package in nightly-2024-06-20(full list with versions):

Stamina

Active – The project has reached a stable, usable state and is being actively developed. Hackage CI status

A retry Haskell library for humans:

  • Exponential backoff with jitter between retries.
  • Limit the attempts of retries and total time.
  • Stamina.HTTP for retrying retriable Network.HTTP.Client exceptions respecting Retry-After headers.
  • Introspectable retry state for logging using RetryStatus, including the last exception that occurred.
  • Support resetting the retry state when for long-running tasks with an attempt that works.

API

Basics

  • Stamina.defaults :: (MonadIO m) => m RetrySettings
  • Stamina.RetryStatus = RetryStatus { attempts :: Int, delay :: NominalDiffTime, totalDelay :: NominalDiffTime, resetInitial :: IO (), lastException :: Maybe SomeException }
  • Stamina.retry :: (MonadCatch m, MonadIO m) => RetrySettings -> (RetryStatus -> m a) -> m a

Exceptions

  • Stamina.RetryAction = RaiseException | Retry | RetryDelay NominalDiffTime | RetryTime UTCTime
  • Stamina.retryFor :: (MonadCatch m, MonadIO m, Exception exc) => RetrySettings -> (exc -> m RetryAction) -> (RetryStatus -> m a) -> m a

HTTP

  • Stamina.HTTP.retry :: (MonadIO m, MonadCatch m) => Stamina.RetrySettings -> (Stamina.RetryStatus -> m a) -> m a

Basic example

import qualified Stamina
import Control.Monad.Catch (throwM)
import Control.Monad.IO.Class (MonadIO)

go :: IO ()
go = Stamina.retry Stamina.defaults $ \retryStatus -> do
  throwM $ userError "nope"

Example to catch specific exceptions


handler :: (MonadIO m) => IOError -> m Stamina.RetryAction
handler _ = return Stamina.Retry

go2 :: IO ()
go2 = Stamina.retryFor Stamina.defaults handler $ \retryStatus -> do
  throwM $ userError "nope"

Development

  1. Install devenv.sh.

  2. devenv shell

  3. stack build

Credits

main = undefined

Changes

Revision history for stamina

0.1.0.3 (2024-01-26)

  • Fix typo
  • Add Stamina.indefiniteDefaults

0.1.0.2 (2024-01-03)

  • Fix haddock
  • Get rid of head usage

0.1.0.1 (2023-12-30)

  • Fix haddock and include README

0.1.0.0 (2023-12-30)

  • First version. Released on an unsuspecting world.