The monadyssey
library is a powerful TypeScript toolkit designed to enhance the development of
robust applications by introducing a series of advanced data structures and control flow mechanisms.
With its roots in functional programming principles, monadyssey
aims to solve common challenges in
application development, particularly around list handling, asynchronous operations, and error management.
At the heart of monadyssey
lies the embrace of functional programming paradigms. By leveraging
pure functions, immutability, and advanced type constructs, the library offers a way to write clearer,
more predictable code. It abstracts away common boilerplate for asynchronous operations and error
handling, allowing developers to focus on business logic rather than control flow intricacies.
- Non-Empty Lists: Recognizing the common pitfall of empty list handling, monadyssey introduces the NonEmptyList type. This guarantees at compile-time that a list contains at least one element, eliminating a class of runtime errors and simplifying list operations by removing the need to check for list emptiness.
- Retryable Asynchronous Operations: Asynchronous operations are a cornerstone of modern application
development, but they often require complex retry logic to handle transient failures gracefully.
monadyssey
provides aSchedule
class, paired with a Policy configuration, to declaratively manage retries, delays, and timeouts, making operations more resilient. - Comprehensive Error Handling: With the
IO
data type,monadyssey
wraps asynchronous effects in a structure that explicitly models both success and failure. This approach encourages rigorous error handling, ensuring that errors are not overlooked and can be transformed or recovered from in a structured manner.
- Type Safety: By leveraging TypeScript's advanced type system,
monadyssey
helps catch errors at compile-time, reducing the risk of runtime exceptions and ensuring code adheres to specified behaviors. - Composability: The library's use of monads and other functional constructs enables the composition of operations in a clear and logical manner. This composability extends to error handling and retry logic, allowing complex behaviors to be built from simpler, understandable pieces.
- Simplification of Async/Await Patterns: While async/await syntax has made asynchronous code more
readable, managing retries, parallel executions, and error handling can still lead to complex code.
monadyssey
simplifies these patterns, offering a higher-level abstraction that maintains readability and reduces boilerplate.
A generic class representing a list that contains at least one element. It is constructed with a head (the first element) and a tail (an array of zero or more elements).
Methods:
size
: Returns the total number of elements in the list.all
: Retrieves all elements of the list as an array.get(index: number)
: Retrieves an element at a specified index.fromArray(value: A[])
: Creates a new NonEmptyList from an array.filter(f)
: Filters elements based on a predicate function.map(f)
: Applies a function to each element, creating a new NonEmptyList.flatMap(f)
: Applies a function returning NonEmptyList to each element, flattening the result.traverse(f)
: Applies an asynchronous function to each element, awaiting all promises.foldLeft
,foldRight
: Reduces the elements to a single value using an accumulator function.
An interface defining the configuration for retry policies, used in conjunction with Schedule
to manage retries
for asynchronous operations.
A class that implements retry logic for IO operations based on a defined Policy. It supports retrying operations based on a condition, repeating operations, and applying timeouts.
Methods:
retryIf(f, condition, liftE)
: Retries an IO operation based on a condition.repeat(f, liftE)
: Repeats an IO operation according to the policy.withTimeout(f, liftE)
: Applies a timeout to an IO operation.
Error types:
Custom error classes are provided to represent various error conditions, including
PolicyValidationError
, TimeoutError
, RetryError
, and RepeatError
.
A class representing an encapsulated asynchronous operation (effect)
that may result in a success (Ok<A>
) or an error (Err<E>
).
Factory Methods:
of(f)
: Creates an IO instance from an asynchronous function.ofSync(f)
: Wraps a synchronous function within IO.ok(value)
,err(error)
: Creates instances of Ok and Err, respectively.
Instance Methods:
map(f)
,mapError(f)
,flatMap(f)
: Transform the success value or error, or chain another IO operation.recover(f)
: Attempts to recover from an error by applying a provided function.runAsync()
: Executes the encapsulated asynchronous effect.
Utility Methods:
zip2(f1, f2)
,zip3(f1, f2, f3)
: Combines multiple IO operations into a single operation, executing them in parallel.
This library is designed to be used in TypeScript applications where functional programming patterns are preferred for managing asynchronous operations, ensuring safety from empty lists, and handling errors in a structured way.
To see specific examples of how to use each component, please refer to the method descriptions and comments within the source code.