fxdart 0.6.2

A functional programming library for Dart, ported from FxTS. Lazy evaluation, concurrent async iteration, and pipeline-style composition.

0.6.2

Docs

• Version-agnostic wording across README, the docs site, and the agent skills: feature descriptions no longer name the release that introduced them (versions live here in the CHANGELOG).

0.6.1

Docs

• README: added typed errors description

0.6.0

Added — typed errors (the Kotlin Arrow 2.x approach, ported)

• Raise<E> + builders (either, eitherAsync, nullable, nullableAsync, foldRaise, foldRaiseAsync): write straight-line Dart inside a scope that can short-circuit with a typed error; Either appears only at the boundary. No TaskEither/IO wrapper tower — Dart's own Future/throw is the effect system, exactly as Arrow uses Kotlin's. Foreign-scope signals rethrow (nesting is safe), leaked scopes throw a descriptive RaiseLeakedError, and the signal is an Error so on Exception never swallows it.

• Scope vocabulary (RaiseOps): bind, bindAll, ensure, ensureNotNull (null-promoting), recover, withError.

• catching / catchingAsync and Either.catching / Either.catchingWith — exception boundaries that always rethrow the raise signal first.

• Either<L, R> (sealed Left/Right, exhaustive switch), with a curated Arrow 2.x method set: fold, map, mapLeft, flatMap, swap, getOrNull, getOrElse, onLeft/onRight, recover, toEitherNel.

• NonEmptyList<T> / Nel<T> — zero-cost extension type (needs SDK ≥ 3.3, hence the floor bump), the error carrier for accumulation.

• Error accumulation (the Arrow replacement for Validated): r.accumulate with lazily-detonating Accumulateds, r.mapOrAccumulate, r.zipOrAccumulate2..5, r.bindNel.

• Pipeline integration: rights, lefts, separateEither, sequenceEither(Async), mapOrAccumulate(Async) as top-level ops and as Fx/FxAsync chain terminals — fail-slow concurrent validation rides the existing concurrent(n) back-channel.

• New agent skill (skills/fxdart-typed-errors/) teaching AI coding assistants the typed-error system — when to reach for either blocks vs plain Dart, accumulation recipes, fpdart migration mappings, and the safety pitfalls. The existing fxdart-pipelines skill cross-references it.

Changed

• SDK floor raised from >=3.0.0 to >=3.3.0 (extension types).

0.5.4

Docs

• README: new CTA badge linking to the Dart vs FxDart comparison site — 50 side-by-side native-Dart vs fxdart examples with an honest verdict on each.

0.5.3

Added

• AI agent skill (skills/fxdart-pipelines/) following the Agent Skills spec — teaches coding assistants when to reach for fxdart (collections, bounded-concurrency Futures, Streams, complex flow logic) and the patterns/pitfalls that matter. Compatible with the community skills CLI (skills get fxdart).
• dart run fxdart:install_skills (also fxdart_skills via dart pub global activate fxdart) — zero-dependency installer that copies the bundled skills into Claude Code, Codex, Devin, Antigravity, OpenCode, pi, or generic .agents/skills/ directories, project-local or --global, with --list and --remove.

0.5.2

Docs

• Documented the full public API — every fx() / async chain method, the Dart-idiomatic aliases, the async iterator protocol types (Concurrent, IterResult, …), and the .curried / .uncurried extensions now carry dartdoc comments. Coverage went from 65.7 % to ~100 % of the exported API.

Packaging

• Moved the runnable Dart example to example/fxdart_example.dart so pub.dev recognises it (was nested under example/dart_example/).

0.5.1

Docs

• List the by-key aggregates (sumBy, averageBy, minBy, maxBy) in the README operator table.

0.5.0

Added

• averageBy (+ averageByAsync, and .averageBy() on the fx() and async chains). The mean of a key over every element — one walk tracking a running total and count. Empty input returns NaN (the average contract). Completes the by-key family (sumBy / maxBy / minBy).

0.4.0

Added

• sumBy (+ sumByAsync, and .sumBy() on the fx() and async chains). Sums a key of every element — map + sum in one terminal, so "total this field" is one call. Empty input returns 0 (the sum contract); the async variant awaits the key extractor per element. Dart-native addition in the maxBy/minBy family (Kotlin's sumOf).

0.3.0

Added

• maxBy / minBy (+ maxByAsync / minByAsync, and .maxBy() / .minBy() on the fx() and async chains). Returns the element with the largest/smallest key in one O(n) walk — the answer to the sortBy(key).head() anti-pattern, which sorts the whole pipeline to read one value. Keys compare like sortBy (Comparable.compare), ties keep the first element encountered, empty input returns null (like head/last). Dart-native addition — FxTS ships only the numeric min/max; the name follows Kotlin's maxByOrNull shape.

0.2.2

Renamed for Dart idiom

• toArray → toList, toArrayAsync → toListAsync (breaking). Dart has no "array" type — these have always returned a List, so they now carry the Dart-standard name. Applies to the top-level functions and the fx() / async chain terminals. The old names are removed outright (not aliased): replace toArray() → toList() and toArrayAsync() → toListAsync().

Dart-idiomatic aliases added (both spellings supported)

Every FxTS operator whose Dart Iterable/collection counterpart has a different established name now exposes both names — the FxTS name for parity and the Dart-idiomatic name as a first-class alias. Nothing is removed (that was toArray's special case above); existing code keeps working, and the FxDart 101 course teaches the Dart-idiomatic spelling. Aliases exist at every level: the top-level functions (+ their *Async twins), the fx() chain, and the async FxAsync chain. On the sync chain several Dart names come for free because Fx extends Iterable (Dart 3): firstOrNull, lastOrNull, elementAtOrNull, any, forEach, length, indexed, nonNulls, contains.

Type-name aliases — the FxTS name claims a type Dart doesn't have:

FxTS name	Dart-idiomatic alias
unicodeToArray	unicodeToList
isBoolean	isBool
isNumber	isNum
isDate	isDateTime

Standard-library vocabulary aliases:

FxTS name	Dart-idiomatic alias
head	firstOrNull
last	lastOrNull
nth	elementAtOrNull
find	firstWhereOrNull
findIndex	indexWhere
some	any
size	count (or .length on the chain)
each	forEach
filter	where
reject	whereNot
flatMap	expand
flat	flattened
drop / dropWhile	skip / skipWhile
uniq / uniqBy	distinct / distinctBy
zipWithIndex	indexed
compact	nonNulls
toSorted	sorted
takeRight	takeLast

includes keeps only its FxTS spelling at the top level — a top-level contains would collide with package:test's matcher; use the inherited .contains() on the chain for the Dart idiom. See test/dart_aliases_test.dart for the both-spellings contract.

Left as-is — already Dart-idiomatic or intentionally FP with no stdlib counterpart: map, take, takeWhile, reduce, fold, join, sum/min/max/average, every, isEmpty, isNull/isNotNull, isString/isList/isMap, and the combinator/pipe family (identity, tap, memoize, curried, pipe, …).

0.2.1

• READEME.md update

0.2.0

• Comprehensive docs site overhaul: tutorials for curried/uncurried and createSeededRandom now part of the FxDart 101 course with live in-browser playground examples.
• Logo and branding refresh for docs site.
• Enhanced playground bundle with full currying extensions support.

0.1.3

• Docs site: new tutorials for curried/uncurried and createSeededRandom (previously undocumented), wired into the FxDart 101 course; the playground bundle now includes the currying extensions.

0.1.2

• .curried / .uncurried extension getters (arity 2–5): a fully typed, Dart-native replacement for FxTS curry, resolved statically per arity. Design rationale in WHY_CURRIED.md. The untyped curry stub's deprecation now points at .curried.

0.1.1

• concurrentPool now eagerly keeps its pool full (FxTS behavior): even one-pull-at-a-time consumers like toArray() get full overlap and completion-order results.
• Docs site (GitHub Pages) with a live in-browser playground for every function, under docs/.

0.1.0

• Complete rewrite: port of FxTS to Dart.
• Lazy sync operators over plain Iterables (map, filter, take, chunk, zip, ...).
• Pull-based FxAsyncIterable protocol with FxTS-style concurrent(n) / concurrentPool(n) evaluation and Stream bridges (fromStream, toStream).
• Typed fx() / FxAsync chain API; dynamic pipe / pipeLazy for parity.
• Strict functions (reduce, groupBy, sortBy, partition, ...), Map-based object functions (omit, pick, evolve, isMatch, ...), and Util (debounce, throttle, shuffle).
• Unportable TS APIs kept as @Deprecated stubs (curry, isUndefined, isArray, isObject).
• 850+ tests ported from the FxTS spec suite.

0.0.1

• Initial update, Add concept inspired by FxJs