gleam/retry

retry executes a fallible operation multiple times. Various aspects can be configured: the number of retry attempts, the duration between attempts, the strategy for adjusting wait times, and the types of errors that should trigger a retry.

Types

Config

opaque </>

pub opaque type Config(a, b)

RetryError

</>

Represents errors that can occur during a retry attempts.

pub type RetryError(a) {
  RetriesExhausted(errors: List(a))
  UnallowedError(error: a)
}

Constructors

```
RetriesExhausted(errors: List(a))
```
Indicates that all retry attempts have been exhausted. Contains an ordered list of all errors encountered during the execution attempts.
```
UnallowedError(error: a)
```
Indicates that retry ran into an error that wasn’t allowed. Contains the specific error that caused the retry to stop. By default, all errors are allowed. Use the allow() function to specify which errors should trigger a retry.

Functions

allow

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pub fn allow(
  config: Config(a, b),
  allow allow: fn(b) -> Bool,
) -> Config(a, b)

Sets the logic for determining whether an error should trigger a retry. Expects a function that takes an error and returns a boolean. Use this function to match on your error types and return True for errors that should trigger a retry, and False for errors that should not.

backoff

</>

pub fn backoff(
  config: Config(a, b),
  next_wait_time next_wait_time: fn(Int) -> Int,
) -> Config(a, b)

Sets the backoff strategy for increasing wait times between retry attempts. Expects a function that takes the previous wait time and returns a the next wait time.

execute

</>

pub fn execute(
  config: Config(a, b),
  operation operation: fn() -> Result(a, b),
) -> Result(a, RetryError(b))

Initiates the retry operation with the provided configuration and operation.

Returns Ok(a) if the operation succeeds, or Error(RetryError(b)).

new

</>

pub fn new(
  max_attempts max_attempts: Int,
  wait_time wait_time: Int,
) -> Config(a, b)

Creates a new configuration with the specified max_attempts and wait_time.

Configuration defaults:

next_wait_time: constant
allow: all errors