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. Part of the skills-for-java project
74
67%
Does it follow best practices?
Impact
Pending
No eval scenarios have been run
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./skills/142-java-functional-programming/SKILL.mdQuality
Discovery
100%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is a strong skill description that comprehensively lists specific functional programming capabilities in Java, includes a clear 'Use when' trigger clause, and uses natural developer terminology throughout. The description is highly distinctive with its focus on the intersection of functional programming and Java. The only minor weakness is that the description is quite long and dense, which could be slightly more scannable, but the content quality is excellent.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | The description lists numerous specific concrete actions and concepts: 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, sealed classes, Stream Gatherers, currying/partial application, effect boundary separation, and concurrent-safe functional patterns. | 3 / 3 |
Completeness | The description explicitly answers both 'what' (applying functional programming principles in Java with a comprehensive list of specific techniques) and 'when' (opens with 'Use when you need to apply functional programming principles in Java'), providing clear trigger guidance. | 3 / 3 |
Trigger Term Quality | Excellent coverage of natural terms a Java developer would use: 'functional programming', 'immutable objects', 'Records', 'lambda expressions', 'Stream API', 'Optional', 'null safety', 'pattern matching', 'sealed classes', 'currying', 'higher-order functions'. These are all terms users would naturally mention when seeking help with functional Java. | 3 / 3 |
Distinctiveness Conflict Risk | The description carves out a very clear niche — functional programming specifically in Java — with highly specific trigger terms like 'Stream API', 'Records', 'sealed classes', 'Stream Gatherers', and 'currying' that are unlikely to conflict with other skills. The combination of Java + functional programming paradigm is distinctive. | 3 / 3 |
Total | 12 / 12 Passed |
Implementation
35%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This skill is essentially a table of contents and a pointer to a reference file, with no concrete code examples or actionable patterns in the body itself. While it correctly identifies compilation safety as a constraint and links to a detailed reference, the SKILL.md provides almost no standalone value — Claude would need to read the reference file to do anything useful. The content would benefit significantly from at least a few inline good/bad code examples for the most common patterns.
Suggestions
Add 2-3 inline code examples showing good vs bad patterns for the most common functional programming transformations (e.g., Stream pipeline, Optional usage, Record vs mutable class) so the skill has standalone actionable value.
Convert the constraints section into a numbered workflow: 1. Compile → 2. Read reference → 3. Apply changes → 4. Verify → 5. If verify fails, fix and re-verify.
Remove the 'What is covered' bullet list or condense it to a single sentence — it restates the description without adding actionable guidance.
Add a concrete example of a before/after refactoring to make the skill immediately actionable without requiring the reference file.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The 'What is covered' section is essentially a table of contents that restates the description without adding actionable value. The constraints section has some redundancy (e.g., 'If compilation fails, stop immediately' is stated twice). However, it's not excessively verbose overall. | 2 / 3 |
Actionability | The skill contains zero code examples, no concrete commands beyond compile/verify, and entirely delegates to a reference file for actual guidance. There is nothing copy-paste ready or executable that teaches a functional programming pattern. | 1 / 3 |
Workflow Clarity | There is a clear sequence implied (compile first → read reference → apply changes → verify), and validation checkpoints are explicitly mentioned. However, the workflow is not fully sequenced with numbered steps and lacks a feedback loop for the verify step. | 2 / 3 |
Progressive Disclosure | There is a single reference file linked, which is appropriate progressive disclosure. However, the SKILL.md itself provides almost no substantive quick-start content — it's essentially just a pointer to the reference with a long bullet list of topics, offering no standalone value. | 2 / 3 |
Total | 7 / 12 Passed |
Validation
100%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 11 / 11 Passed
Validation for skill structure
No warnings or errors.
- Repository
- jabrena/cursor-rules-java
- Commit
9ec21dd
- Reviewed
Table of Contents
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