go-style-core

Go Style Core Principles

Style Principles (Priority Order)

When writing readable Go code, apply these principles in order of importance:

Priority Order

1. Clarity — Can a reader understand the code without extra context?
2. Simplicity — Is this the simplest way to accomplish the goal?
3. Concision — Does every line earn its place?
4. Maintainability — Will this be easy to modify later?
5. Consistency — Does it match surrounding code and project conventions?

Read references/PRINCIPLES.md when resolving conflicts between clarity, simplicity, and concision, or when you need concrete examples of how each principle applies in real Go code.

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Formatting

Run gofmt — no exceptions. There is no rigid line length limit, but Uber suggests a soft limit of 99 characters. Break by semantics, not length — refactor rather than just wrap.

Read references/FORMATTING.md when configuring gofmt, deciding on line breaks, applying MixedCaps rules, or resolving local consistency questions.

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Reduce Nesting

Handle error cases and special conditions first. Return early or continue the loop to keep the "happy path" unindented.

// Bad: Deeply nested
for _, v := range data {
    if v.F1 == 1 {
        v = process(v)
        if err := v.Call(); err == nil {
            v.Send()
        } else {
            return err
        }
    } else {
        log.Printf("Invalid v: %v", v)
    }
}

// Good: Flat structure with early returns
for _, v := range data {
    if v.F1 != 1 {
        log.Printf("Invalid v: %v", v)
        continue
    }

    v = process(v)
    if err := v.Call(); err != nil {
        return err
    }
    v.Send()
}

Unnecessary Else

If a variable is set in both branches of an if, use default + override pattern.

// Bad: Setting in both branches
var a int
if b {
    a = 100
} else {
    a = 10
}

// Good: Default + override
a := 10
if b {
    a = 100
}

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Naked Returns

A return statement without arguments returns the named return values. This is known as a "naked" return.

func split(sum int) (x, y int) {
    x = sum * 4 / 9
    y = sum - x
    return // returns x, y
}

Guidelines for Naked Returns

• OK in small functions: Naked returns are fine in functions that are just a handful of lines
• Be explicit in medium+ functions: Once a function grows to medium size, be explicit with return values for clarity
• Don't name results just for naked returns: Clarity of documentation is always more important than saving a line or two

// Good: Small function, naked return is clear
func minMax(a, b int) (min, max int) {
    if a < b {
        min, max = a, b
    } else {
        min, max = b, a
    }
    return
}

// Good: Larger function, explicit return
func processData(data []byte) (result []byte, err error) {
    result = make([]byte, 0, len(data))

    for _, b := range data {
        if b == 0 {
            return nil, errors.New("null byte in data")
        }
        result = append(result, transform(b))
    }

    return result, nil // explicit: clearer in longer functions
}

See go-documentation for guidance on Named Result Parameters.

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Semicolons

Go's lexer automatically inserts semicolons after any line whose last token is an identifier, literal, or one of: break continue fallthrough return ++ -- ) }.

This means opening braces must be on the same line as the control structure:

// Good: brace on same line
if i < f() {
    g()
}

// Bad: brace on next line — lexer inserts semicolon after f()
if i < f()  // wrong!
{           // wrong!
    g()
}

Idiomatic Go only has explicit semicolons in for loop clauses and to separate multiple statements on a single line.

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Quick Reference

Principle	Key Question
Clarity	Can a reader understand what and why?
Simplicity	Is this the simplest approach?
Concision	Is the signal-to-noise ratio high?
Maintainability	Can this be safely modified later?
Consistency	Does this match surrounding code?

Related Skills

• Naming conventions: See go-naming when applying MixedCaps, choosing identifier names, or resolving naming debates
• Error flow: See go-error-handling when structuring error-first guard clauses or reducing nesting via early returns
• Documentation: See go-documentation when writing doc comments, named return parameters, or package-level docs
• Linting enforcement: See go-linting when automating style checks with golangci-lint or configuring CI
• Code review: See go-code-review when applying style principles during a systematic code review
• Logging style: See go-logging when reviewing logging practices, choosing between log and slog, or structuring log output