Claude prompt for code generation: Pure Function (Starter)
Claude · Code Generation · Starter
You are a pragmatic coach using Claude for code generation, specifically pure function.
Job: small testable unit.
Audience: engineers. Constraint: types + tests.
Working style: plain and encouraging. Optimize for first successful run with safe defaults.
Process:
1. Restate the brief in one sentence and list missing facts as questions.
2. Draft the artifact.
3. Stress-test it against the constraint.
4. Return a final version plus 3 numbered improvements.
Output contract: use headings, short paragraphs, and concrete examples. No filler. No invented statistics.
If information is missing, make the smallest reasonable assumption and label it.A strong Claude code generation pure function prompt names the job, audience, and finish line. This page does that for engineers. In practice, one customization pass is enough when the brief is this specific. The starter version uses plain and encouraging language and targets first successful run with safe defaults.
When to use this prompt
Picture a engineers professional opening Claude with one job: pure function. Without "types + tests", answers drift. This page prevents that drift. Bookmark this page if you run pure function weekly.
Why this prompt works
- Locks the audience (engineers) before style so tone stays honest.
- Names a clear job so Claude does not wander into generic advice.
- Forces an output contract: headings, examples, and a final version.
- Uses plain and encouraging language that matches how practitioners actually brief work.
- Keeps code generation vocabulary specific instead of buzzwords.
How to use it in Claude
Name the success metric aloud: small testable unit. If the draft cannot pass it, do not polish prose yet. For code generation work, paste claude handles long briefs, policy-aware writing, and stepwise reasoning as a one-line reminder above the prompt. Add one real example from your last week of work so the model mirrors your domain. Paste the prompt into Claude and replace bracketed details with your facts. When engineers review output, they should see first successful run with safe defaults without hunting for it.
Swap the audience once. If the pure function piece still works, the core is solid. For pure function in code generation, the failure mode is usually vague audience. This prompt blocks that by design — especially "types + tests". Expect two minutes customizing and two minutes editing for Starter output. Anthropic models still need your facts for pure function; they cannot invent metrics or brand rules. developers teams bookmark slug pure-function-starter when first successful run with safe defaults matters.
Step-by-step
- Open Claude and paste the prompt block unchanged.
- Replace placeholders with your project facts (engineers, offer, timeline).
- Confirm the constraint is still visible: types + tests.
- If output is vague, ask Claude to restate assumptions as questions first.
- Reply with one fix list, then regenerate the final version only.
Example output
Example output shape: H1 with Pure Function, 3 short sections, bullet list of recommendations, closing line that states types + tests. Facts you supply appear; nothing invented.
Common mistakes
- Pasting confidential data instead of redacted placeholders.
- Asking for pure function plus three other jobs in one message.
- Deleting "types + tests" to save space — that is usually the whole point.
Expert notes
This Claude page targets "small testable unit" for engineers. Claude handles long briefs, policy-aware writing, and stepwise reasoning. The plain and encouraging tone keeps first successful run with safe defaults visible while you edit.
Workflow tip: save three winning outputs for pure function and diff them. The shared skeleton becomes your team standard inside Claude.
Comparison / variations
| Approach | When | Tweak |
|---|---|---|
| Bare request | You only need a spark | Write a pure function piece. |
| This prompt | You need a usable draft | Role, constraint, steps, and output contract included. |
| Plus examples | Voice must match yours | Paste 120 words of your writing or a still you like, then rerun in Claude. |
Key takeaways
- engineers should recognize themselves in the first paragraph.
- Ship a draft, then tighten. Do not chase a perfect first token.
- The Starter variant is for first successful run with safe defaults.
- State the job (small testable unit) in one line before any style talk.
- Keep types + tests visible in the prompt, not only in your head.
FAQ
- What is a Claude prompt for pure function?
- It is a structured brief that tells Claude how to produce code generation output for engineers. This starter version stresses first successful run with safe defaults and keeps "types + tests" in the instructions.
- How do I customize this Claude code generation prompt?
- Swap project nouns, paste one real example, and leave the process steps intact. The constraint "types + tests" should stay unless your brief truly changed.
- Why use the starter angle for pure function?
- Different angles solve different failures. Starter helps when engineers need first successful run with safe defaults. It is not longer for its own sake — each line has a job.
- Is this Claude prompt updated for 2026?
- Yes. Pages follow our SEO Bible, refresh on a rolling schedule, and include current best practices for Anthropic models. Always verify facts before client delivery.