go-patterns

Go Patterns Skill

This skill provides comprehensive guidance on modern Go patterns, idioms, and best practices, with special focus on features introduced in Go 1.18 and later.

When to Use

Activate this skill when:

• Writing idiomatic Go code
• Implementing design patterns in Go
• Using modern Go features (generics, fuzzing, workspaces)
• Refactoring code to be more idiomatic
• Teaching Go best practices
• Code review for idiom compliance

Modern Go Features

Generics (Go 1.18+)

Type Parameters:

// Generic function
func Map[T, U any](slice []T, f func(T) U) []U {
    result := make([]U, len(slice))
    for i, v := range slice {
        result[i] = f(v)
    }
    return result
}

// Usage
numbers := []int{1, 2, 3, 4, 5}
doubled := Map(numbers, func(n int) int { return n * 2 })

Type Constraints:

// Ordered constraint
type Ordered interface {
    ~int | ~int8 | ~int16 | ~int32 | ~int64 |
    ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 |
    ~float32 | ~float64 | ~string
}

func Min[T Ordered](a, b T) T {
    if a < b {
        return a
    }
    return b
}

// Custom constraints
type Numeric interface {
    ~int | ~int64 | ~float64
}

func Sum[T Numeric](values []T) T {
    var sum T
    for _, v := range values {
        sum += v
    }
    return sum
}

Generic Data Structures:

// Generic stack
type Stack[T any] struct {
    items []T
}

func NewStack[T any]() *Stack[T] {
    return &Stack[T]{items: make([]T, 0)}
}

func (s *Stack[T]) Push(item T) {
    s.items = append(s.items, item)
}

func (s *Stack[T]) Pop() (T, bool) {
    if len(s.items) == 0 {
        var zero T
        return zero, false
    }
    item := s.items[len(s.items)-1]
    s.items = s.items[:len(s.items)-1]
    return item, true
}

// Generic map utilities
func Keys[K comparable, V any](m map[K]V) []K {
    keys := make([]K, 0, len(m))
    for k := range m {
        keys = append(keys, k)
    }
    return keys
}

func Values[K comparable, V any](m map[K]V) []V {
    values := make([]V, 0, len(m))
    for _, v := range m {
        values = append(values, v)
    }
    return values
}