Effect Patterns Hub

Purpose: Provide quick access to 130+ curated Effect-TS patterns from the EffectPatterns repository. Use this skill to find specific implementation patterns, compare approaches, and reference best practices.

Triggers

• Looking for a specific Effect pattern or idiom

• Need real-world examples of Effect concepts

• Want to see multiple approaches to the same problem

• Comparing implementation strategies

• Learning new Effect features

Pattern Library Location

Local Patterns: .claude/skills/effect-patterns-hub/patterns/

Documentation: docs/effect-patterns/

Count: 130+ patterns in MDX format

Quick Decision Tree

I need to...

Create Effects

• From value → constructor-succeed-some-right.mdx

• From sync code → constructor-sync-async.mdx

• From promise → constructor-try-trypromise.mdx

• From nullable → constructor-from-nullable-option-either.mdx

• Pre-resolved → create-pre-resolved-effect.mdx

Transform & Compose

• Map values → combinator-map.mdx

• Chain effects → combinator-flatmap.mdx

• Sequence operations → combinator-sequencing.mdx

• Combine values → combinator-zip.mdx

• Filter → combinator-filter.mdx

• Conditional logic → combinator-conditional.mdx

• Process collections → combinator-foreach-all.mdx

Control Flow

• Sequential logic → write-sequential-code-with-gen.mdx

• Business logic → use-gen-for-business-logic.mdx

• Pipe composition → use-pipe-for-composition.mdx

• Branching workflows → conditionally-branching-workflows.mdx

• Combinators → control-flow-with-combinators.mdx

• Repetition → control-repetition-with-schedule.mdx

Error Handling

• Define errors → define-tagged-errors.mdx

• Catch specific errors → pattern-catchtag.mdx

• Handle all errors → handle-errors-with-catch.mdx

• Retry operations → retry-based-on-specific-errors.mdx

• Flaky operations → handle-flaky-operations-with-retry-timeout.mdx

• Map errors → mapping-errors-to-fit-your-domain.mdx

• Handle unexpected → handle-unexpected-errors-with-cause.mdx

• API errors → handle-api-errors.mdx

Concurrency

• Parallel execution → run-effects-in-parallel-with-all.mdx

• Background tasks → run-background-tasks-with-fork.mdx

• Process collections → process-collection-in-parallel-with-foreach.mdx

• Race effects → race-concurrent-effects.mdx

• Fibers explained → understand-fibers-as-lightweight-threads.mdx

• Decouple with queues → decouple-fibers-with-queue-pubsub.mdx

• Polling → poll-for-status-until-task-completes.mdx

• Graceful shutdown → implement-graceful-shutdown.mdx

Services & Dependency Injection

• Model dependencies → model-dependencies-as-services.mdx

• Understand layers → understand-layers-for-dependency-injection.mdx

• Scoped services → scoped-service-layer.mdx

• Composable modules → organize-layers-into-composable-modules.mdx

• Compose scoped layers → compose-scoped-layers.mdx

• Provide config → provide-config-layer.mdx

• Caching wrapper → add-caching-by-wrapping-a-layer.mdx

Resource Management

• Bracket pattern → safely-bracket-resource-usage.mdx

• Scope management → manage-resource-lifecycles-with-scope.mdx

• Manual scope → manual-scope-management.mdx

• Scoped resources runtime → create-managed-runtime-for-scoped-resources.mdx

Streaming

• Process streaming data → process-streaming-data-with-stream.mdx

• From iterable → stream-from-iterable.mdx

• From file → stream-from-file.mdx

• From paginated API → stream-from-paginated-api.mdx

• Concurrent processing → stream-process-concurrently.mdx

• Batch processing → stream-process-in-batches.mdx

• Collect results → stream-collect-results.mdx

• Run for effects → stream-run-for-effects.mdx

• Manage resources → stream-manage-resources.mdx

• Retry on failure → stream-retry-on-failure.mdx

Schema & Validation

• Define contracts → define-contracts-with-schema.mdx

• Parse/decode → parse-with-schema-decode.mdx

• Transform data → transform-data-with-schema.mdx

• Validate body → validate-request-body.mdx

• Brand types → brand-model-domain-type.mdx

• Brand validation → brand-validate-parse.mdx

• Config schema → define-config-schema.mdx

Data Types

• Option → data-option.mdx , model-optional-values-with-option.mdx

• Either → data-either.mdx , accumulate-multiple-errors-with-either.mdx

• Chunk → data-chunk.mdx , use-chunk-for-high-performance-collections.mdx

• Array → data-array.mdx

• HashSet → data-hashset.mdx

• Duration → data-duration.mdx , representing-time-spans-with-duration.mdx

• DateTime → data-datetime.mdx , beyond-the-date-type.mdx

• BigDecimal → data-bigdecimal.mdx

• Cause → data-cause.mdx

• Exit → data-exit.mdx

• Ref → data-ref.mdx , manage-shared-state-with-ref.mdx

• Redacted → data-redacted.mdx

• Case → data-case.mdx

• Class → data-class.mdx

• Struct → data-struct.mdx

• Tuple → data-tuple.mdx

Pattern Matching

• Match API → pattern-match.mdx

• Effectful match → pattern-matcheffect.mdx

• Tag matching → pattern-matchtag.mdx

• Option/Either checks → pattern-option-either-checks.mdx

HTTP & Web

• Basic HTTP server → build-a-basic-http-server.mdx

• Launch server → launch-http-server.mdx

• Handle GET → handle-get-request.mdx

• HTTP client request → make-http-client-request.mdx

• Testable HTTP client → create-a-testable-http-client-service.mdx

• JSON response → send-json-response.mdx

• Path parameters → extract-path-parameters.mdx

• Provide dependencies to routes → provide-dependencies-to-routes.mdx

Testing

• Mocking dependencies → mocking-dependencies-in-tests.mdx

• Use Default layer → use-default-layer-for-tests.mdx

• Tests adapt to code → write-tests-that-adapt-to-application-code.mdx

Observability

• Structured logging → leverage-structured-logging.mdx , observability-structured-logging.mdx

• Tracing spans → trace-operations-with-spans.mdx , observability-tracing-spans.mdx

• Custom metrics → add-custom-metrics.mdx , observability-custom-metrics.mdx

• OpenTelemetry → observability-opentelemetry.mdx

• Effect.fn instrumentation → observability-effect-fn.mdx

Runtime & Execution

• runPromise → execute-with-runpromise.mdx

• runSync → execute-with-runsync.mdx

• runFork → execute-long-running-apps-with-runfork.mdx

• Reusable runtime → create-reusable-runtime-from-layers.mdx

Configuration

• Access config → access-config-in-context.mdx

• Define schema → define-config-schema.mdx

• Provide layer → provide-config-layer.mdx

Time & Scheduling

• Current time → accessing-current-time-with-clock.mdx

• Duration → representing-time-spans-with-duration.mdx

• DateTime → beyond-the-date-type.mdx

• Schedule repetition → control-repetition-with-schedule.mdx

Project Setup

• New project → setup-new-project.mdx

• Editor LSP → supercharge-your-editor-with-the-effect-lsp.mdx

• AI agents MCP → teach-your-ai-agents-effect-with-the-mcp-server.mdx

Advanced Concepts

• Structural equality → comparing-data-by-value-with-structural-equality.mdx

• Effect channels → understand-effect-channels.mdx

• Effects are lazy → effects-are-lazy.mdx

• Not found vs errors → distinguish-not-found-from-errors.mdx

• Promise problems → solve-promise-problems-with-effect.mdx

• Avoid long chains → avoid-long-andthen-chains.mdx

Pattern Categories

By Skill Level

Beginner (Getting Started)

• Constructor patterns (succeed, fail, sync, async)

• Basic combinators (map, flatMap, tap)

• Simple error handling (catch, catchTag)

• Effect.gen basics

• runPromise/runSync

Intermediate (Building Applications)

• Services and layers

• Schema validation

• HTTP servers and clients

• Resource management

• Concurrency basics (Effect.all, fork)

• Testing with mocks

Advanced (Production Systems)

• Complex layer composition

• Custom runtimes

• Streaming pipelines

• Graceful shutdown

• OpenTelemetry integration

• Performance optimization (Chunk, Ref)

By Use Case

Domain Modeling

• Schema definitions

• Brand types

• Tagged errors

• Option/Either for optional/fallible values

API Development

• HTTP server setup

• Route handling

• Request validation

• Error handling

• Response formatting

Data Processing

• Stream processing

• Batch operations

• Parallel processing

• Resource-safe pipelines

Application Architecture

• Service layer design

• Dependency injection

• Module composition

• Configuration management

Testing

• Mock layers

• Test utilities

• Testable services

Observability

• Structured logging

• Distributed tracing

• Custom metrics

• Performance monitoring

Search Patterns

By Keyword

Use Grep to search patterns by keyword:

Find patterns about error handling

grep -l "error" patterns/*.mdx

Find patterns about concurrency

grep -l "concurrent|parallel|fiber" patterns/*.mdx

Find patterns about HTTP

grep -l "http|server|client" patterns/*.mdx

Find patterns about testing

grep -l "test|mock" patterns/*.mdx

By Frontmatter Tags

All patterns include metadata:

• title : Human-readable name

• id : Unique identifier (filename without extension)

• skillLevel : beginner, intermediate, advanced

• useCase : domain-modeling, error-handling, concurrency, etc.

• summary : Brief description

• tags : Keywords for searching

• related : Links to related patterns

Common Searches

"How do I create an Effect from..."

• → Search constructor patterns: grep -l "constructor" patterns/*.mdx

• → Check constructor-*.mdx files

"How do I handle errors when..."

• → Search error handling: grep -l "error|catch|retry" patterns/*.mdx

• → Check handle-*.mdx and pattern-catchtag.mdx

"How do I run multiple things concurrently?"

• → Search concurrency: grep -l "concurrent|parallel|all|fork" patterns/*.mdx

• → Check run-effects-in-parallel-with-all.mdx

"How do I work with services?"

• → Search services: grep -l "service|layer|dependency" patterns/*.mdx

• → Check model-dependencies-as-services.mdx , understand-layers-for-dependency-injection.mdx

"How do I validate data?"

• → Search schema: grep -l "schema|validate|parse" patterns/*.mdx

• → Check define-contracts-with-schema.mdx , parse-with-schema-decode.mdx

Integration with Other Skills

Foundations → Patterns Hub

When you need concrete examples for foundation concepts, check patterns:

• effect-foundations teaches concepts → patterns show implementation

Architect → Patterns Hub

When designing systems, reference architectural patterns:

• Layer composition → organize-layers-into-composable-modules.mdx

• Service design → model-dependencies-as-services.mdx

• Scoped resources → scoped-service-layer.mdx

Engineer → Patterns Hub

When implementing features, find relevant patterns:

• HTTP endpoints → handle-get-request.mdx , validate-request-body.mdx

• Error handling → retry-based-on-specific-errors.mdx

• Concurrency → run-effects-in-parallel-with-all.mdx

Tester → Patterns Hub

When writing tests, reference testing patterns:

• Mock services → mocking-dependencies-in-tests.mdx

• Test layers → use-default-layer-for-tests.mdx

• Testable design → write-tests-that-adapt-to-application-code.mdx

Usage Workflow

• Identify Need: "I need to [do something] with Effect"

• Check Decision Tree: Find relevant section above

• Read Pattern: Use Read tool on the pattern file

• Adapt to Context: Apply pattern to your specific use case

• Check Related: Follow related links in pattern frontmatter

• Consult Agent: If unclear, use @effect-engineer or @effect-architect

Anti-Pattern Detection

If you find yourself:

• Using imperative loops → Check process-collection-in-parallel-with-foreach.mdx

• Mixing promises and Effects → Check constructor-try-trypromise.mdx , solve-promise-problems-with-effect.mdx

• Long andThen chains → Check avoid-long-andthen-chains.mdx , use-gen-for-business-logic.mdx

• Leaking requirements → Check model-dependencies-as-services.mdx

• Manual resource cleanup → Check safely-bracket-resource-usage.mdx

Pattern File Structure

Each pattern file follows this structure:

title: Human-readable title id: kebab-case-id skillLevel: beginner | intermediate | advanced useCase: primary-use-case summary: Brief description tags:

• keyword1
• keyword2 related:
• related-pattern-id-1
• related-pattern-id-2 author: Author name

Title

Guideline

What to do

Rationale

Why do it this way

Good Example

✅ Recommended approach

Bad Example

❌ What to avoid

Related Patterns

Links to related patterns

Maintenance

Patterns are synced from EffectPatterns repository.

To update patterns:

cd /tmp git clone --depth=1 https://github.com/PaulJPhilp/EffectPatterns.git cp -r EffectPatterns/content/published/* /Users/pooks/Dev/crate/.claude/skills/effect-patterns-hub/patterns/ cp -r EffectPatterns/content/published/* /Users/pooks/Dev/crate/docs/effect-patterns/

Summary

• 130+ patterns covering all Effect-TS concepts

• Decision tree for quick pattern lookup

• Integration with existing skills and agents

• Searchable by keyword, use case, skill level

• Examples showing good and bad practices

• Related patterns for deeper exploration

Use this skill as your go-to reference for "How do I... with Effect?"