daxle 2.0.0

A lightweight Dart utility package offering common abstractions and missing features to write safer, more expressive code.

2.0.0 - 2026-06-27

• BREAKING CHANGES / API REWRITE:

  • Removed Result<T, E> type. Use Either<L, R> or TaskEither<L, R> for representing fallible operations.
  • Removed Lazy<T> type. Use deferred pipelines or standard closures.
  • Redesigned Option<T> as a sealed class with direct subclasses Some<T> and None<T>. This allows full compile-time exhaustive pattern matching.
  • Redesigned Either<L, R> as a sealed class with direct subclasses Left<L, R> and Right<L, R> for compile-time exhaustive pattern matching.
  • Changed Option.getOrElse to take an eager default value T instead of a resolver callback.
  • Changed Either.getOrElse to take a resolver callback R Function(L left) instead of an eager default value.

• NEW FEATURES:

  • Added TaskEither<L, R> type to represent lazy, asynchronous computations that can fail (Future<Either<L, R>>), supporting monadic chaining (map, flatMap, orElse, fold).
  • Added Pipeline<T> and AsyncPipeline<T> classes to build deferred, type-safe operation chains.
    • Supports observational side-effects (tap).
    • Supports recovery from errors (recover and recoverWith).
    • Supports error mapping (mapError).
    • Supports cleanup logic (finalize / finally equivalent).
    • Supports folding success and failure states.
    • Supports concurrent combination of asynchronous pipelines (zip).
  • Added Unit type and unit constant to represent the absence of a meaningful value.
  • Added zipped(), map(), flatMap(), and filter() extension methods on Dart 3 Record tuples of size 2, 3, 4, and 5 containing Option, Either, or TaskEither values (runs TaskEither tasks concurrently).
  • Added Option.fromPredicate and Either.cond factory constructors, and Option.filter method for clean, explicit conditional evaluation.

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1.1.0

• Introduced Lazy type for lazy evaluation and memoization of values.
• Supported transforming Lazy to Result, Option, and Either.

1.0.0

• Initial version. (2026-01-10)
  • Implemented Either type for representing success or failure.
  • Implemented Option type for representing the presence or absence of a value.
  • Implemented Result type for representing a result of an operation that can either succeed or fail.