142-java-functional-programming

Use when you need to apply functional programming principles in Java — including writing immutable objects and Records, pure functions, functional interfaces, lambda expressions, Stream API pipelines, Optional for null safety, function composition, higher-order functions, pattern matching for instanceof and switch, sealed classes/interfaces for controlled hierarchies, Stream Gatherers for custom operations, currying/partial application, effect boundary separation, and concurrent-safe functional patterns. This should trigger for requests such as Improve the code with Functional Programming; Apply Functional Programming; Refactor the code with Functional Programming. Part of cursor-rules-java project

Quality

—

Does it follow best practices?

Impact

—

No eval scenarios have been run

Securityby

Passed

No known issues

Quality

Content

70%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

Well-structured with a clear validated workflow and clean one-level progressive disclosure, but it loses points for description-duplicating content and for leaving the actual refactoring guidance vague and deferred.

Suggestions

Remove or condense the 'What is covered' and 'When to use' sections since they repeat the frontmatter description, reclaiming tokens.

Add one or two concrete good/bad code snippets inline (or a sharper, example-anchored instruction in step 4) so the core refactoring action is not purely abstract.

Dimension	Reasoning	Score
Conciseness	The body is largely free of concept-explanation fluff, but the 'What is covered in this Skill?' list and 'When to use this skill' section duplicate the description's enumeration and triggers, so it could be tightened.	2 / 3
Actionability	Concrete maven commands ('./mvnw compile', 'mvn clean verify') and a specific reference path are present, but the core refactoring step ('Implement selected functional refactorings while keeping side effects at boundaries') is abstract and fully deferred to the reference.	2 / 3
Workflow Clarity	A clear 5-step sequence with explicit validation checkpoints — compile before with stop-on-failure, then 'mvn clean verify' after — providing the feedback loop expected for code-modifying operations.	3 / 3
Progressive Disclosure	The body is an overview that defers detail to a single, well-signaled, one-level-deep reference (references/142-java-functional-programming.md, verified present), linked both in the workflow and a dedicated Reference section.	3 / 3
	Total	10 / 12 Passed

Description

90%

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description with explicit what/when coverage and natural trigger phrases; its only weakness is second-person voice ('you need to apply'), which lowers the specificity score.

Suggestions

Rewrite in third person (e.g., 'Applies functional programming principles in Java') to avoid the second-person voice penalty.

Trim the very long capability enumeration to keep the description concise without losing the key triggers.

Dimension	Reasoning	Score
Specificity	Lists many concrete actions ('writing immutable objects and Records, pure functions, functional interfaces, lambda expressions, Stream API pipelines'), but uses second person ('Use when you need to apply'), so the voice penalty reduces the base score of 3 by 1.	2 / 3
Completeness	Explicitly answers both what (the enumerated capability list) and when ('Use when you need to apply functional programming principles in Java' plus the trigger examples), satisfying the explicit-trigger requirement.	3 / 3
Trigger Term Quality	Provides natural phrases users would say — 'Improve the code with Functional Programming; Apply Functional Programming; Refactor the code with Functional Programming' — giving good coverage of likely trigger terms.	3 / 3
Distinctiveness Conflict Risk	Targets a clear Java functional-programming niche with distinct triggers, making it unlikely to fire for unrelated skills.	3 / 3
	Total	11 / 12 Passed

Validation

100%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 16 / 16 Passed

Validation for skill structure

No warnings or errors.

Repository: jabrena/cursor-rules-java
Commit: 86eb63d

Reviewed: 4 days ago

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