Add agentic workflow for systematic functional programming improvements

[Copilot]

Automates detection and application of moderate functional programming techniques: immutability patterns, functional initialization, and transformative operations (map/filter/reduce).

Workflow

Functional Programming Enhancer - Scheduled Tuesday/Thursday, creates PRs with improvements found in pkg/ Go code.

Detection Strategy

Phase 1: Discovery

• Pattern match var declarations with single assignment
• Find empty slice/map initialization followed by incremental building
• Identify imperative loops that transform data
• Prioritize by safety/clarity impact and risk level

Phase 2: Analysis

• Serena MCP semantic analysis for top 10-15 opportunities
• Context review: dependencies, side effects, test coverage
• Design transformation with Go idioms in mind

Phase 3: Implementation

• Convert mutable patterns to immutable
• Replace multi-step init with composite literals
• Add functional helpers (map/filter/reduce) only if used 3+ times
• Inline loops when clearer than abstractions

Phase 4: Validation

• Run tests and linters
• Manual review for clarity improvements

Example Transformations

// Immutability: var → composite literal
var config Config
config.Host = "localhost"
config.Port = 8080
// →
config := Config{Host: "localhost", Port: 8080}

// Functional init: incremental → declarative
result := make([]string, 0)
result = append(result, item1)
result = append(result, item2)
// →
result := []string{item1, item2}

// Transformative: imperative loop → functional pattern
var activeNames []string
for _, item := range items {
    if item.Active {
        activeNames = append(activeNames, item.Name)
    }
}
// →
activeNames := sliceutil.Map(
    sliceutil.Filter(items, func(i Item) bool { return i.Active }),
    func(i Item) string { return i.Name },
)

Configuration

• Engine: Claude (thoughtful analysis)
• Tools: Serena (semantic Go analysis), GitHub API, edit/bash
• Output: PRs with labels refactoring, functional-programming, code-quality
• Expires: 7d

Pragmatic balance: clarity over dogma, Go idioms over functional purity.

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