go-rust-systems

Go & Rust Systems Programming

When to Use Which

Go Quick Reference

Essential Commands

go mod init <module>          # Initialize new module
go mod tidy                   # Add missing, remove unused
go test -race ./...          # Run with race detector
go test -cover ./...         # Show coverage
golangci-lint run            # Run all linters
govulncheck ./...            # Check vulnerabilities

Critical Patterns

// 1. Always check errors
result, err := someFunc()
if err != nil {
    return fmt.Errorf("operation failed: %w", err)  // Wrap with context
}

// 2. Use context for cancellation
func processData(ctx context.Context, data []string) error {
    for _, item := range data {
        select {
        case <-ctx.Done():
            return ctx.Err()  // Respect cancellation
        default:
            // Process item
        }
    }
    return nil
}

// 3. Defer cleanup immediately
file, err := os.Open("file.txt")
if err != nil {
    return err
}
defer file.Close()  // Defer right after open

// 4. Table-driven tests
func TestAdd(t *testing.T) {
    tests := []struct {
        name string
        a, b int
        want int
    }{
        {"positive", 1, 2, 3},
        {"negative", -1, -2, -3},
    }
    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            if got := Add(tt.a, tt.b); got != tt.want {
                t.Errorf("Add() = %v, want %v", got, tt.want)
            }
        })
    }
}

Control flow: switch vs if / else

Prefer switch for multi-way dispatch on one expression (and type switches); keep if for errors, booleans, guards, and two-branch logic. Do not rewrite errors.Is / errors.As chains just to use switch. Detail: rules/210-go.mdc (Simplicity & Idiomatic Go) and references/go-idioms.md.