Brewing with GitHub Copilot for RPG: How AI Can Modernize Development Without Burning the Coffee

  Today’s Coffee: Dunkin’ Caramel Me Crazy — smooth, sweet, with a caramel kick.

Modernizing RPG development is like brewing a good cup of coffee—you want just the right balance of strength and smoothness. Done right, it energizes your team and brings out rich new flavors. Done wrong, it leaves a bitter aftertaste.

For IBM i RPG developers, GitHub Copilot isn’t just another shiny tool. It’s a practical assistant that helps us:

  • Understand legacy code faster
  • Modernize RPG into free-form syntax
  • Catch errors before production
  • Generate templates, documentation, and build notes
  • Support standards compliance reviews

But like brewing coffee, you need the right process. The more details you give Copilot, the better the outcome.


Why Pair Copilot with RPG?

For decades, RPG developers have relied on SEU, SDA, and fixed-format code. It worked, and in many shops it still does. But just like sticking with instant coffee forever, it limits the experience.

GitHub Copilot, when paired with VS Code or RDi, doesn’t rewrite your world. Instead, it adds value in practical, daily ways:

  • Explaining unfamiliar legacy programs
  • Generating boilerplate free-form RPG code
  • Reviewing code for consistency and quality
  • Writing documentation you’d otherwise skip
  • Even helping debug production issues under tight deadlines

It’s not magic. It’s a helpful partner that lets you move faster while staying in control.


Why Copilot Matters for RPG Developers

  1. Legacy Survival – Many shops are still running 30-year-old RPG programs. Copilot can summarize, explain, and document those programs without hunting down the original author.
  2. Modernization – Converting from RPG II/III or fixed-form to free-form can feel overwhelming. Copilot speeds it up with suggestions, refactoring prompts, and SQL examples.
  3. Standards Compliance – Reviews aren’t fun. Copilot can automate a first pass, flagging missing error handling, outdated specs, or style issues.
  4. Productivity – Instead of staring at a blank member, Copilot can generate scaffolding: service programs, subfiles, stored procedures, or CLLE job control.

Prompt Categories You Can Use

Every Copilot session starts with a good prompt. Here are practical categories:

1. Understanding Legacy Programs

  • Act like a senior RPG developer. Explain in plain language what this program does and its main business logic.
  • Act like a senior RPG developer. Summarize subprocedures, control flow, and all files/tables used.
  • Act like a senior RPG developer. Identify legacy RPG II/III code and suggest free-form refactoring.

2. Pre-Code Review

  • Act like a senior RPG developer. Perform a pre-code review. List violations, outdated RPG formats, and missing error handling.
  • Act like a senior RPG developer. Identify SELECT * SQL statements and un-externalized file specs.

3. Code Review

  • Act like a senior RPG developer. Conduct a full code review and categorize issues as critical, major, or minor.
  • Act like a senior RPG developer. Produce a Markdown report of all violations.

4. Build Notes

  • Act like a senior RPG developer. Generate build notes for this program, including dependencies and free-form status.

5. Code Generation

  • Act like a senior RPG developer. Generate a free-form RPGLE subprocedure with header comments, record locking, and SQL error handling.
  • Act like a senior RPG developer. Generate a CLLE program that calls an RPGLE program with logging.

6. Documentation

  • Act like a senior RPG developer. Generate Markdown documentation: purpose, parameters, files, SQL, and subprocedures.
  • Act like a senior RPG developer. Add inline comments for each subprocedure with inputs, outputs, and errors.

7. SQL Stored Procedures

  • Act like a senior RPG developer. Review this SQL stored procedure for error handling, dynamic SQL risks, and performance considerations.

8. Reverse Engineering

  • Act like a senior RPG developer. Reverse engineer this program. List subprocedures, legacy sections, SQL, and compliance gaps.

9. Debugging Production Bugs

  • Act like a senior RPG developer. Here are the production bug details and affected program. Find the likely cause and propose a solution.

A Detailed Prompt for Standards-Based Reviews

Sometimes you need more than a quick suggestion. You need a structured review. Here’s a detailed prompt template:

Act like a senior RPG developer. Please review the attached code file and provide a compliance score based on our development standards. Use the exact format below and focus on issues that impact functionality, security, maintainability, and adherence to team standards. If you need additional context (standards doc, mod mark, or runtime assumptions), state what you need.

 

## Code Review: [FILENAME]

### Compliant Areas

[List what follows standards correctly]

### ⚠️ Issues Found


#### Critical Issues

[Issues that could cause system failures, data corruption, or security problems]

 

#### Major Issues

[Issues that violate important standards but don't cause immediate failures]

 

#### Minor Issues

[Style, consistency, or maintainability improvements]

 

### 📋 Recommendations

[Provide specific code fixes using markdown code blocks with filepath comments]

 

### 📊 Standards Compliance Score: X%

 

**Summary:** [Brief overall assessment]

 

Scoring Guidelines:

90–100%: Excellent

80–89%: Good

70–79%: Acceptable

60–69%: Poor

Below 60%: Unacceptable

 

Key Areas to Evaluate:

- Documentation

- Error handling

- Naming conventions

- Code structure

- Security

- Performance

- Maintainability

💡 Tip: The more details you add to the prompt—standards doc, mod mark, business context—the sharper and more useful the review becomes.


Final Sip

Using GitHub Copilot for RPG development is like brewing with Dunkin’ Caramel Me Crazy—it’s familiar, sweet, and keeps you going when deadlines are tight.

The key is balance:

  • Give Copilot clear, detailed prompts
  • Start small with code explanations or reviews
  • Use structured prompts for modernization and compliance
  • Always validate Copilot’s suggestions before committing

Modernization doesn’t mean throwing away your RPG mastery—it means amplifying it. Copilot is the extra shot of espresso that makes legacy code understandable, maintainable, and ready for the future.

Follow The RPG Blend for more practical strategies, prompt examples, and leadership insights on IBM i modernization.

 GitHub: 👉 The RPG Blend GitHub Repository


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