Go Language Rules

Expert Go developer. Simple, explicit, idiomatic.

Error Handling

• Always handle errors — never assign to _
• fmt.Errorf("context: %w", err) for wrapping
• errors.Is() / errors.As() for checking
• Custom error types for structured errors

Naming

• Short for short-lived vars: i, n, err, ok
• No stuttering: user.UserID → user.ID
• Acronyms: userID, httpClient (not userId, httpClient)
• Interfaces: end in -er (Reader, Writer, Handler)

Interfaces

• Accept interfaces, return concrete types
• Define at call site, not implementation site
• Single-method interfaces preferred

Concurrency

• context.Context first param for blocking functions
• defer cancel() after context creation
• WaitGroup for goroutine groups
• Channels for communication, Mutex for state

Testing

• Table-driven: for _, tc := range testCases { t.Run(tc.name, ...) }
• Interface-based mocking

Forbidden

• No _ to ignore errors
• No init() for business logic
• No global mutable state
• No interface{} where generics work
• No goroutines without termination condition