dartz_plus 0.3.0

A functional programming library for Dart and Flutter providing type-safe error handling with Either type, functional composition, and async support.

Changelog

All notable changes to this project will be documented in this file.

0.3.0 - 2026-01-03

• Added @MapTo and @IgnoreMap annotations to support advanced object mapping.
• Updated @Mapper annotation to support specifying a target constructor.
• Refactored internal library structure to use part and part of directives.

0.2.0 - 2026-01-03

• Added new type mapper to support auto mapper with dartz_plus_generator package.

0.1.0 - 2025-12-06

Added

• foldAsync: Asynchronous version of fold that accepts both synchronous and asynchronous functions.
• fromNullable: Static method to create an Either from a nullable value.
• cond: Static method to create an Either based on a condition.
• tryCatch: Static method to execute a function and catch any exceptions as a Left.
• filterOrElse: Method to filter Right values, converting to Left if the predicate fails.
• tap: Method to execute a side effect on Right values without changing the result.
• Improved toString implementation for better debugging.
• comprehensive example application showcasing various features:
  • Basic usage
  • Async handling
  • Error handling
  • Functional programming enhancements
  • Real-world API integration
  • Chaining strategies

0.0.1 2025-12-XX

Added

• Initial release of dartz_plus
• Either<L, R> sealed class for representing disjoint union types
• Left<L, R> class representing the left side (typically errors/failures)
• Right<L, R> class representing the right side (typically success values)
• Factory constructors:
  • Either.left(L value) - Creates a Left instance
  • Either.right(R value) - Creates a Right instance
• Getters:
  • isLeft - Returns true if this is a Left instance
  • isRight - Returns true if this is a Right instance
  • leftValue - Returns the left value if this is a Left, otherwise null
  • rightValue - Returns the right value if this is a Right, otherwise null
• Core methods:
  • fold<T>(T Function(L l) left, T Function(R r) right) - Applies the appropriate function based on whether this is a Left or Right
  • foldAsync<T>(FutureOr<T> Function(L l) left, FutureOr<T> Function(R r) right) - Async version of fold that accepts both synchronous and asynchronous functions
  • swap() - Swaps the left and right types
• Transformation methods:
  • map<T>(T Function(R r) f) - Transforms the Right value using the given function
  • mapLeft<T>(T Function(L l) f) - Transforms the Left value using the given function
  • bimap<L2, R2>(L2 Function(L l) left, R2 Function(R r) right) - Transforms both Left and Right values using the given functions
• Composition methods:
  • flatMap<T>(Either<L, T> Function(R r) f) - Chains Either operations (monadic bind)
  • getOrElse(R Function() orElse) - Returns the right value if this is a Right, otherwise returns the result of calling orElse (lazy evaluation)
  • orElse(Either<L, R> Function() alternative) - Returns this Either if it's a Right, otherwise returns the result of calling alternative (lazy evaluation)
• Equatable support for value equality comparison
• Comprehensive test coverage
• README documentation with usage examples

Dependencies

• equatable: ^2.0.7 - For value equality
• flutter SDK - Required for Flutter support

Requirements

• Dart SDK: ^3.10.1
• Flutter SDK