senrecep

Use when representing optional values explicitly — Maybe<T> as a null-safe container, Maybe.From()/FromTry() for creation, HasValue/HasNoValue, Map/Bind chaining, TapNone for None-side effects, Match for consumption, and ToMaybeResult() to bridge into the Result pattern.

Use when handling operation outcomes without exceptions — Result and Result<T> for success/failure, railway-oriented chaining with Then/ThenAsync/Ensure, Match for consumption, and Result.And/Or for combining multiple results.

Use when composing business validation logic — define rules as classes, Func fields, or inline lambdas; combine with .And()/.Or()/.Linear()/.Next(); evaluate with RuleEngine.Evaluate(); branch with RuleEngine.If().

Use when modeling partial success — These<TError, TValue> holds Left (error only), Right (value only), or Both (error + value), enabling scenarios where a result can partially succeed while carrying warnings. Use FromResult to bridge from Result<T>, ToResult/ToResultLenient to bridge back, and Partition to split collections.

Use when you need testable time — IDateTimeProvider wraps clock access so production code uses DateTimeProvider while tests use the built-in FakeDateTimeProvider to freeze/advance/set the clock; also provides .ToDateOnly() and .ToTimeOnly() DateTime extension methods.

Use when adding cross-cutting pipeline behaviors to CQRS handlers — ValidationBehavior (CSharpEssentials.Validation, throws EnhancedValidationException), LoggingBehavior (ILoggableRequest), ExceptionHandlingBehavior (auto-converts exceptions to Result.Failure for Result-returning handlers), CachingBehavior (ICacheable with IDistributedCache), and TransactionScopeBehavior (ITransactionalRequest).

Use when adding transient fault handling around Result-based operations — ResiliencePolicy/ResiliencePolicy<T> for retry, timeout, circuit breaker, and fallback composition backed by Polly v8 with Result-aware retry filtering.

Use when deciding which CSharpEssentials package to use — overview of all 20 packages organized by concern, the meta-package that bundles core functional modules, and a quick-reference table mapping problems to packages.

Use when creating structured error values — Err factory methods (failure/validation/notFound/conflict/unauthorized/forbidden/unexpected/fromException/combine/equals), AppError with code/description/type/metadata, ErrorType enum, and ErrorMetadata namespace.

Use when objects need deep-copy semantics — implement Cloneable<T> on domain objects with custom clone logic, use deepClone() for any value (plain objects, Date, Map, Set, TypedArrays, Error, circular refs — never throws, React Native / Hermes compatible), and cloneArray() to call .clone() on every element in a Cloneable collection.

Use when building DDD domain models — createEntityBase() mixin factory for aggregate roots with audit fields and domain events, createSoftDeletable() for soft deletion lifecycle, and DomainEvent marker interface for event-driven design. Uses composition (private field delegation), not class inheritance.

Use when making HTTP calls that should return Result<T> instead of throwing — fetchResult const object with get/post/put/patch/delete methods, RequestBuilder for fluent header/query-param/body construction with .send<T>(), httpStatusToError for status-to-AppError mapping, extractErrorDescription for ProblemDetails parsing.

Use when representing optional values explicitly — Maybe<T> as a null-safe container with hasValue discriminant, Maybe.from()/some()/none()/fromTry() for creation, map/bind/filter/tap/tapNone chaining, match/switch for consumption, conditional mapIf/bindIf, fallback or/orElse, extraction getOrDefault/getOrElse/getOrUndefined/getOrThrow/deconstruct, flatten/toArray utilities, async support with mapAsync/bindAsync/filterAsync/tapAsync/matchAsync/orAsync, and collection utilities tryFirst/tryLast/tryFind/choose/asMaybe.

Use when deciding which tsentials module to use — overview of all 18 subpath imports organized by concern, install command, and a quick-reference table mapping problems to modules.

Use when handling operation outcomes without exceptions — Result<T> for success/failure, railway-oriented chaining with then/map/ensure, ResultChain for fluent sync pipelines, ResultAsync<T> for async chains that resolve once at the end, Result.combine for merging heterogeneous results, and maybe-bridge for Maybe<->Result conversion.

Use when composing business validation logic — define rules as typed functions returning VoidResult, combine with RuleEngine.and/or/linear/if, evaluate synchronously or asynchronously with evaluateAsync.

Use when writing or editing client-facing prose (report synthesis text, ai-core prompts, marketing copy) - removes AI-sounding patterns so text reads as human-written