Convert Go to Rust

Convert Go code to idiomatic Rust. This skill extends

meta-convert-dev

This Skill Extends

• meta-convert-dev

  - Foundational conversion patterns (APTV workflow, testing strategies)

For general concepts like the Analyze → Plan → Transform → Validate workflow, testing strategies, and common pitfalls, see the meta-skill first.

This Skill Adds

• Type mappings: Go types → Rust types
• Idiom translations: Go patterns → idiomatic Rust
• Error handling: Go error interface → Rust Result<T, E>
• Async patterns: Goroutines/channels → Tokio async/await
• Memory/Ownership: Garbage collection → ownership/borrowing
• Interface patterns: Go interface → Rust trait

This Skill Does NOT Cover

• General conversion methodology - see

  meta-convert-dev

• Go language fundamentals - see

  lang-go-dev

• Rust language fundamentals - see

  lang-rust-dev

• Reverse conversion (Rust → Go) - see

  convert-rust-golang

Quick Reference

string

String

&str

int

i32

i64

uint

u32

u64

float64

f64

bool

bool

[]T

Vec<T>

[N]T

[T; N]

map[K]V

HashMap<K, V>

chan T

mpsc::Sender<T>

Receiver<T>

interface{}

nil

None

Option<T>

error

Result<T, E>

struct

struct

interface

trait

defer

Drop

When Converting Code

1. Analyze source thoroughly before writing target
2. Map types first - create type equivalence table
3. Preserve semantics over syntax similarity
4. Adopt target idioms - don't write "Go code in Rust syntax"
5. Handle edge cases - nil checks, error paths, resource cleanup
6. Test equivalence - same inputs → same outputs

Type System Mapping

Primitive Types

bool

bool

string

String

string

&str

int

isize

int8

i8

int16

i16

int32

rune

i32

int64

i64

uint

usize

uint8

byte

u8

uint16

u16

uint32

u32

uint64

u64

float32

f32

float64

f64

complex64

complex128

Collection Types

[]T

Vec<T>

[]T

&[T]

[N]T

[T; N]

map[K]V

HashMap<K, V>

map[K]V

BTreeMap<K, V>

HashSet<T>

BTreeSet<T>

Composite Types

struct { ... }

struct { ... }

*T

Box<T>

*T

Rc<T>

Arc<T>

interface { ... }

trait Trait { ... }

struct + methods

impl Block

func(T) U

fn(T) -> U

func(T) U

Fn(T) -> U

chan T

mpsc::Sender<T>

<-chan T

mpsc::Receiver<T>

chan<- T

mpsc::Sender<T>

Pointer and Reference Types

*T

Option<Box<T>>

*T

Box<T>

&T

&mut T

&[T]

&HashMap<K, V>

Idiom Translation

Pattern 1: Error Handling with Multiple Returns

Go:

func readFile(path string) ([]byte, error) {
    data, err := os.ReadFile(path)
    if err != nil {
        return nil, fmt.Errorf("failed to read %s: %w", path, err)
    }
    return data, nil
}

Rust:

use std::fs;
use std::path::Path;

fn read_file(path: &Path) -> Result<Vec<u8>, std::io::Error> {
    fs::read(path)
        .map_err(|e| std::io::Error::new(
            e.kind(),
            format!("failed to read {}: {}", path.display(), e)
        ))
}

Why this translation:

• Rust's

  Result<T, E>

  encodes success/failure in the type system
• The

  ?

  operator propagates errors ergonomically
• Error wrapping uses

  map_err

  instead of manual checks
• Borrowed

  &Path

  instead of owned

  String

  for efficiency

Pattern 2: Nil Checking

Go:

func getUserName(user *User) string {
    if user == nil {
        return "Anonymous"
    }
    if user.Name == "" {
        return "Anonymous"
    }
    return user.Name
}

Rust:

fn get_user_name(user: Option<&User>) -> &str {
    user.and_then(|u| {
        if u.name.is_empty() {
            None
        } else {
            Some(u.name.as_str())
        }
    })
    .unwrap_or("Anonymous")
}

// Or more idiomatically with pattern matching:
fn get_user_name(user: Option<&User>) -> &str {
    match user {
        Some(u) if !u.name.is_empty() => &u.name,
        _ => "Anonymous",
    }
}

Why this translation:

• Option<T>

  makes nullability explicit in the type system
• Combinators like

  and_then

  and

  unwrap_or

  are idiomatic
• Pattern matching with guards is more readable
• Borrowed references avoid unnecessary cloning

Pattern 3: Interface Implementation

Go:

type Reader interface {
    Read(p []byte) (n int, err error)
}

type FileReader struct {
    path string
}

func (f *FileReader) Read(p []byte) (int, error) {
    // Implementation
    return len(p), nil
}

func processReader(r Reader) error {
    buf := make([]byte, 1024)
    n, err := r.Read(buf)
    if err != nil {
        return err
    }
    // Process n bytes
    return nil
}

Rust:

use std::io::{self, Read};

trait Reader {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize>;
}

struct FileReader {
    path: String,
}

impl Reader for FileReader {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        // Implementation
        Ok(buf.len())
    }
}

fn process_reader<R: Reader>(r: &mut R) -> io::Result<()> {
    let mut buf = vec![0u8; 1024];
    let n = r.read(&mut buf)?;
    // Process n bytes
    Ok(())
}

Why this translation:

• Rust traits are explicitly implemented with

  impl Trait for Type

• Generic functions use trait bounds (

  <R: Reader>

  )
• Mutable borrows (

  &mut

  ) make mutation explicit
• The

  ?

  operator replaces verbose error checking

Pattern 4: Goroutines and Channels

Go:

func processItems(items []string) []string {
    results := make(chan string, len(items))

    for _, item := range items {
        go func(s string) {
            results <- processItem(s)
        }(item)
    }

    var processed []string
    for i := 0; i < len(items); i++ {
        processed = append(processed, <-results)
    }
    return processed
}

Rust:

use tokio::task;

async fn process_items(items: Vec<String>) -> Vec<String> {
    let handles: Vec<_> = items
        .into_iter()
        .map(|item| {
            task::spawn(async move {
                process_item(item).await
            })
        })
        .collect();

    let mut processed = Vec::new();
    for handle in handles {
        if let Ok(result) = handle.await {
            processed.push(result);
        }
    }
    processed
}

Why this translation:

• Tokio's async/await is more explicit about async boundaries

• task::spawn

  creates async tasks similar to goroutines
• Awaiting task handles is more type-safe than channels
• Move semantics avoid accidental captures
• Alternative: Use channels with

  tokio::sync::mpsc

  for Go-like patterns

Pattern 5: Defer for Cleanup

Go:

func processFile(path string) error {
    f, err := os.Open(path)
    if err != nil {
        return err
    }
    defer f.Close()

    // Work with file
    return process(f)
}

Rust:

use std::fs::File;
use std::path::Path;

fn process_file(path: &Path) -> std::io::Result<()> {
    let f = File::open(path)?;

    // Work with file
    process(&f)
    // f.close() called automatically via Drop
}

// Or with explicit scope control:
fn process_file_scoped(path: &Path) -> std::io::Result<()> {
    let result = {
        let f = File::open(path)?;
        process(&f)
    }; // f dropped here
    result
}

Why this translation:

• Rust's RAII (Drop trait) automatically cleans up resources
• No need for explicit

  defer

  statements
• Scope-based cleanup is deterministic
• More type-safe than runtime defer

Pattern 6: Type Assertions and Type Switches

Go:

func handleValue(v interface{}) string {
    switch val := v.(type) {
    case string:
        return fmt.Sprintf("string: %s", val)
    case int:
        return fmt.Sprintf("int: %d", val)
    case error:
        return fmt.Sprintf("error: %v", val)
    default:
        return "unknown"
    }
}

Rust:

// Use enums instead of interface{} for type-safe variants
enum Value {
    String(String),
    Int(i32),
    Error(String),
}

fn handle_value(v: Value) -> String {
    match v {
        Value::String(s) => format!("string: {}", s),
        Value::Int(i) => format!("int: {}", i),
        Value::Error(e) => format!("error: {}", e),
    }
}

// Or use trait objects with downcasting (less idiomatic):
use std::any::Any;

fn handle_any(v: &dyn Any) -> String {
    if let Some(s) = v.downcast_ref::<String>() {
        format!("string: {}", s)
    } else if let Some(i) = v.downcast_ref::<i32>() {
        format!("int: {}", i)
    } else {
        "unknown".to_string()
    }
}

Why this translation:

• Rust enums are type-safe alternatives to

  interface{}

• Pattern matching exhaustively handles all variants
• Compiler ensures all cases are covered
• Avoid

  Any

  downcasting when possible (use enums instead)

Pattern 7: Method Receivers (Value vs Pointer)

Go:

type Counter struct {
    count int
}

// Pointer receiver (mutates)
func (c *Counter) Increment() {
    c.count++
}

// Value receiver (doesn't mutate)
func (c Counter) Value() int {
    return c.count
}

Rust:

struct Counter {
    count: i32,
}

impl Counter {
    // Mutable reference (mutates)
    fn increment(&mut self) {
        self.count += 1;
    }

    // Immutable reference (doesn't mutate)
    fn value(&self) -> i32 {
        self.count
    }

    // Consuming method (takes ownership)
    fn into_inner(self) -> i32 {
        self.count
    }
}

Why this translation:

• Rust makes mutability explicit:

  &self

  ,

  &mut self

  ,

  self

• Borrowing prevents accidental copies
• Consuming methods (

  self

  ) transfer ownership
• More explicit control over mutation

Pattern 8: Struct Embedding (Composition)

Go:

type Base struct {
    ID int
}

func (b *Base) GetID() int {
    return b.ID
}

type Derived struct {
    Base
    Name string
}

func main() {
    d := Derived{
        Base: Base{ID: 1},
        Name: "test",
    }
    fmt.Println(d.GetID()) // Method promoted from Base
}

Rust:

struct Base {
    id: i32,
}

impl Base {
    fn get_id(&self) -> i32 {
        self.id
    }
}

struct Derived {
    base: Base,
    name: String,
}

impl Derived {
    // Explicit delegation (no automatic promotion)
    fn get_id(&self) -> i32 {
        self.base.get_id()
    }
}

// Or use Deref trait for automatic field access:
use std::ops::Deref;

impl Deref for Derived {
    type Target = Base;

    fn deref(&self) -> &Self::Target {
        &self.base
    }
}

Why this translation:

• Rust favors explicit composition over embedding
• No automatic method promotion (use delegation)

• Deref

  trait can provide field access convenience
• More explicit about the relationship

Pattern 9: Context Propagation

Go:

func fetchData(ctx context.Context, url string) ([]byte, error) {
    req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
    if err != nil {
        return nil, err
    }

    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()

    return io.ReadAll(resp.Body)
}

Rust:

use tokio::time::{timeout, Duration};
use reqwest;

async fn fetch_data(url: &str, timeout_ms: u64) -> Result<Vec<u8>, reqwest::Error> {
    let response = timeout(
        Duration::from_millis(timeout_ms),
        reqwest::get(url)
    )
    .await
    .map_err(|_| reqwest::Error::from(std::io::Error::new(
        std::io::ErrorKind::TimedOut,
        "request timed out"
    )))??;

    response.bytes()
        .await
        .map(|b| b.to_vec())
}

// Or with explicit cancellation token:
use tokio_util::sync::CancellationToken;

async fn fetch_data_cancellable(
    url: &str,
    cancel_token: CancellationToken,
) -> Result<Vec<u8>, reqwest::Error> {
    tokio::select! {
        result = reqwest::get(url) => {
            result?.bytes().await.map(|b| b.to_vec())
        }
        _ = cancel_token.cancelled() => {
            Err(reqwest::Error::from(std::io::Error::new(
                std::io::ErrorKind::Interrupted,
                "cancelled"
            )))
        }
    }
}

Why this translation:

• Rust doesn't have built-in context; use timeout or cancellation tokens

• tokio::select!

  provides cancellation semantics
• Explicit timeout durations instead of context deadlines
• More type-safe cancellation handling

Pattern 10: Variadic Functions

Go:

func sum(nums ...int) int {
    total := 0
    for _, n := range nums {
        total += n
    }
    return total
}

func main() {
    fmt.Println(sum(1, 2, 3, 4))
}

Rust:

fn sum(nums: &[i32]) -> i32 {
    nums.iter().sum()
}

fn main() {
    println!("{}", sum(&[1, 2, 3, 4]));
}

// Or with macro for syntax sugar:
macro_rules! sum {
    ($($x:expr),*) => {
        {
            let nums = [$($x),*];
            nums.iter().sum::<i32>()
        }
    };
}

fn main() {
    println!("{}", sum!(1, 2, 3, 4));
}

Why this translation:

• Rust doesn't have variadic functions; use slices
• Macros can provide variadic-like syntax
• Iterator methods are more idiomatic than loops
• More explicit about allocation

Error Handling

Go Error Interface → Rust Result Type

Go's

error

Result<T, E>

Philosophy Shift:

• Go: Errors are values, checked explicitly via

  if err != nil

• Rust: Errors are types, propagated with

  ?

  operator

Basic Error Translation

Go:

func divide(a, b float64) (float64, error) {
    if b == 0 {
        return 0, errors.New("division by zero")
    }
    return a / b, nil
}

func main() {
    result, err := divide(10, 0)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(result)
}

Rust:

use std::error::Error;
use std::fmt;

#[derive(Debug)]
struct DivisionError;

impl fmt::Display for DivisionError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "division by zero")
    }
}

impl Error for DivisionError {}

fn divide(a: f64, b: f64) -> Result<f64, DivisionError> {
    if b == 0.0 {
        Err(DivisionError)
    } else {
        Ok(a / b)
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let result = divide(10.0, 0.0)?;
    println!("{}", result);
    Ok(())
}

Error Wrapping and Context

Go:

func readConfig(path string) (*Config, error) {
    data, err := os.ReadFile(path)
    if err != nil {
        return nil, fmt.Errorf("failed to read config: %w", err)
    }

    var cfg Config
    if err := json.Unmarshal(data, &cfg); err != nil {
        return nil, fmt.Errorf("failed to parse config: %w", err)
    }

    return &cfg, nil
}

Rust:

use std::fs;
use std::path::Path;
use serde::Deserialize;
use thiserror::Error;

#[derive(Debug, Error)]
enum ConfigError {
    #[error("failed to read config: {0}")]
    ReadFailed(#[from] std::io::Error),

    #[error("failed to parse config: {0}")]
    ParseFailed(#[from] serde_json::Error),
}

#[derive(Deserialize)]
struct Config {
    // fields
}

fn read_config(path: &Path) -> Result<Config, ConfigError> {
    let data = fs::read_to_string(path)?;
    let cfg: Config = serde_json::from_str(&data)?;
    Ok(cfg)
}

Custom Error Types

Go:

type ValidationError struct {
    Field   string
    Message string
}

func (e *ValidationError) Error() string {
    return fmt.Sprintf("validation failed for %s: %s", e.Field, e.Message)
}

func validate(user *User) error {
    if user.Email == "" {
        return &ValidationError{
            Field:   "email",
            Message: "cannot be empty",
        }
    }
    return nil
}

Rust:

use thiserror::Error;

#[derive(Debug, Error)]
#[error("validation failed for {field}: {message}")]
struct ValidationError {
    field: String,
    message: String,
}

fn validate(user: &User) -> Result<(), ValidationError> {
    if user.email.is_empty() {
        return Err(ValidationError {
            field: "email".to_string(),
            message: "cannot be empty".to_string(),
        });
    }
    Ok(())
}

Error Handling Best Practices

if err != nil { return nil, err }

?

fmt.Errorf("context: %w", err)

map_err(|e| ...)

enum

#[from]

errors.Is(err, target)

match

errors.As(err, &target)

downcast_ref

enum Error { NotFound }

Concurrency Patterns

Goroutines → Async Tasks

Philosophy Shift:

• Go: Goroutines are cheap threads, blocking is fine
• Rust: Async tasks are cooperative, blocking requires special handling

Basic Goroutine Translation

Go:

func fetchAll(urls []string) []Result {
    results := make(chan Result, len(urls))

    for _, url := range urls {
        go func(u string) {
            results <- fetch(u)
        }(url)
    }

    var out []Result
    for i := 0; i < len(urls); i++ {
        out = append(out, <-results)
    }
    return out
}

Rust (with Tokio):

use tokio::task;

async fn fetch_all(urls: Vec<String>) -> Vec<Result> {
    let handles: Vec<_> = urls
        .into_iter()
        .map(|url| task::spawn(async move { fetch(&url).await }))
        .collect();

    let mut out = Vec::new();
    for handle in handles {
        if let Ok(result) = handle.await {
            out.push(result);
        }
    }
    out
}

// Or using futures::join_all:
use futures::future::join_all;

async fn fetch_all(urls: Vec<String>) -> Vec<Result> {
    join_all(urls.iter().map(|url| fetch(url))).await
}

Channels Translation

Go:

func producer(ch chan<- int) {
    for i := 0; i < 10; i++ {
        ch <- i
    }
    close(ch)
}

func consumer(ch <-chan int) {
    for val := range ch {
        fmt.Println(val)
    }
}

func main() {
    ch := make(chan int, 5)
    go producer(ch)
    consumer(ch)
}

Rust:

use tokio::sync::mpsc;

async fn producer(tx: mpsc::Sender<i32>) {
    for i in 0..10 {
        let _ = tx.send(i).await;
    }
    // Channel closes when tx is dropped
}

async fn consumer(mut rx: mpsc::Receiver<i32>) {
    while let Some(val) = rx.recv().await {
        println!("{}", val);
    }
}

#[tokio::main]
async fn main() {
    let (tx, rx) = mpsc::channel(5);

    tokio::spawn(async move {
        producer(tx).await;
    });

    consumer(rx).await;
}

Select Statement Translation

Go:

func waitForFirst(ch1, ch2 <-chan string) string {
    select {
    case msg := <-ch1:
        return msg
    case msg := <-ch2:
        return msg
    case <-time.After(1 * time.Second):
        return "timeout"
    }
}

Rust:

use tokio::sync::mpsc;
use tokio::time::{sleep, Duration};

async fn wait_for_first(
    mut rx1: mpsc::Receiver<String>,
    mut rx2: mpsc::Receiver<String>,
) -> String {
    tokio::select! {
        Some(msg) = rx1.recv() => msg,
        Some(msg) = rx2.recv() => msg,
        _ = sleep(Duration::from_secs(1)) => "timeout".to_string(),
    }
}

Worker Pool Pattern

Go:

func workerPool(jobs <-chan Job, results chan<- Result, numWorkers int) {
    var wg sync.WaitGroup

    for i := 0; i < numWorkers; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            for job := range jobs {
                results <- process(job)
            }
        }()
    }

    wg.Wait()
    close(results)
}

Rust:

use tokio::sync::mpsc;
use tokio::task;

async fn worker_pool(
    mut jobs: mpsc::Receiver<Job>,
    results: mpsc::Sender<Result>,
    num_workers: usize,
) {
    let mut handles = vec![];

    for _ in 0..num_workers {
        let mut jobs = jobs.clone();
        let results = results.clone();

        let handle = task::spawn(async move {
            while let Some(job) = jobs.recv().await {
                let result = process(job).await;
                let _ = results.send(result).await;
            }
        });

        handles.push(handle);
    }

    drop(jobs); // Close the receiver

    for handle in handles {
        let _ = handle.await;
    }
    // results sender dropped, channel closes
}

Sync Primitives Translation

sync.Mutex

std::sync::Mutex

sync.RWMutex

std::sync::RwLock

sync.WaitGroup

JoinHandle

sync.Once

std::sync::Once

sync.Cond

std::sync::Condvar

atomic.*

std::sync::atomic::*

chan T

tokio::sync::mpsc

chan T

std::sync::mpsc

Async Best Practices

1. Don't block in async: Use

   tokio::task::spawn_blocking

   for CPU-bound work
2. Prefer bounded channels: Prevent unbounded memory growth
3. Use

   tokio::select!

   carefully: Branches are not evaluated in order
4. Handle task panics: Use

   JoinHandle::await

   and check results
5. Use

   Arc

   for shared state: Wrap with

   Mutex

   or

   RwLock

   for mutation

Memory & Ownership

Garbage Collection → Ownership System

Philosophy Shift:

• Go: GC handles memory, share references freely
• Rust: Ownership rules enforced at compile time, explicit sharing

Ownership Rules in Rust

1. Each value has exactly one owner
2. When the owner goes out of scope, the value is dropped
3. Values can be borrowed (referenced) immutably or mutably
4. Only one mutable borrow OR multiple immutable borrows at a time

Basic Ownership Translation

Go:

func process() {
    data := []int{1, 2, 3, 4, 5}

    // Pass by reference (slice is a reference type)
    modifyData(data)

    // data is modified
    fmt.Println(data)
}

func modifyData(d []int) {
    d[0] = 99
}

Rust:

fn process() {
    let mut data = vec![1, 2, 3, 4, 5];

    // Pass mutable borrow
    modify_data(&mut data);

    // data is modified
    println!("{:?}", data);
}

fn modify_data(d: &mut Vec<i32>) {
    d[0] = 99;
}

Shared Ownership (Reference Counting)

Go:

type Cache struct {
    data map[string]*Value
}

func (c *Cache) Get(key string) *Value {
    return c.data[key] // Returns pointer, GC handles lifetime
}

func main() {
    cache := &Cache{data: make(map[string]*Value)}
    val := cache.Get("key")
    // val can outlive cache in Go (GC prevents dangling pointers)
}

Rust:

use std::sync::Arc;
use std::collections::HashMap;

struct Cache {
    data: HashMap<String, Arc<Value>>,
}

impl Cache {
    fn get(&self, key: &str) -> Option<Arc<Value>> {
        self.data.get(key).cloned() // Clone the Arc, not the Value
    }
}

fn main() {
    let cache = Cache { data: HashMap::new() };
    let val = cache.get("key");
    // val holds a reference count to Value
}

Move Semantics

Go:

func transfer() {
    data := []int{1, 2, 3}

    // Both variables point to same backing array
    newData := data

    // Both can be used
    fmt.Println(data)
    fmt.Println(newData)
}

Rust:

fn transfer() {
    let data = vec![1, 2, 3];

    // Ownership moved to new_data
    let new_data = data;

    // Error: data is no longer valid
    // println!("{:?}", data); // Compile error!

    println!("{:?}", new_data); // OK
}

// To keep using data, clone it:
fn transfer_with_clone() {
    let data = vec![1, 2, 3];
    let new_data = data.clone(); // Explicit copy

    println!("{:?}", data);     // OK
    println!("{:?}", new_data); // OK
}

Borrowing Rules

Go:

func example() {
    data := []int{1, 2, 3}

    // Can pass to multiple functions
    read1(data)
    read2(data)
    modify(data)
}

func read1(d []int) { /* read only */ }
func read2(d []int) { /* read only */ }
func modify(d []int) { d[0] = 99 }

Rust:

fn example() {
    let mut data = vec![1, 2, 3];

    // Multiple immutable borrows OK
    read1(&data);
    read2(&data);

    // Mutable borrow (must be exclusive)
    modify(&mut data);

    // Cannot have immutable and mutable borrows simultaneously:
    // read1(&data);
    // modify(&mut data); // Compile error!
}

fn read1(d: &Vec<i32>) { /* read only */ }
fn read2(d: &Vec<i32>) { /* read only */ }
fn modify(d: &mut Vec<i32>) { d[0] = 99; }

Lifetime Annotations

Go:

type Parser struct {
    source string
}

func (p *Parser) NextToken() string {
    // Returns slice of source string
    // GC ensures source outlives the token
    return p.source[0:5]
}

Rust:

struct Parser<'a> {
    source: &'a str,
}

impl<'a> Parser<'a> {
    fn next_token(&self) -> &'a str {
        // Lifetime 'a ensures returned slice
        // doesn't outlive source
        &self.source[0..5]
    }
}

Interior Mutability

Go:

type Counter struct {
    mu    sync.Mutex
    count int
}

func (c *Counter) Increment() {
    c.mu.Lock()
    defer c.mu.Unlock()
    c.count++
}

func (c *Counter) Value() int {
    c.mu.Lock()
    defer c.mu.Unlock()
    return c.count
}

Rust:

use std::sync::Mutex;

struct Counter {
    count: Mutex<i32>,
}

impl Counter {
    fn increment(&self) {
        let mut count = self.count.lock().unwrap();
        *count += 1;
    }

    fn value(&self) -> i32 {
        *self.count.lock().unwrap()
    }
}

Memory Ownership Decision Tree

Does data need to be shared across threads?
├─ YES → Arc<T> (thread-safe reference counting)
│        ├─ Needs mutation? → Arc<Mutex<T>> or Arc<RwLock<T>>
│        └─ Read-only? → Arc<T>
└─ NO  → Single-threaded sharing
         ├─ Needs mutation? → Rc<RefCell<T>>
         ├─ Read-only? → Rc<T>
         └─ Exclusive ownership? → Box<T> or owned value

Common Pitfalls

1. Trying to Return Borrowed References Without Lifetimes

Problem:

// Go allows this easily:
// func getData() *Data {
//     d := Data{}
//     return &d  // GC keeps this alive
// }

// Rust compile error:
fn get_data() -> &Data {
    let d = Data::new();
    &d  // Error: returns reference to local variable
}

Solution:

// Return owned value instead:
fn get_data() -> Data {
    Data::new()
}

// Or use Box for heap allocation:
fn get_data() -> Box<Data> {
    Box::new(Data::new())
}

2. Fighting the Borrow Checker with Cloning

Problem:

// Cloning everything to avoid borrow checker errors
fn process(data: Vec<Item>) -> Vec<Result> {
    data.clone() // Unnecessary clone
        .iter()
        .map(|item| expensive_operation(item.clone())) // Unnecessary clone
        .collect()
}

Solution:

// Use borrows instead:
fn process(data: &[Item]) -> Vec<Result> {
    data.iter()
        .map(|item| expensive_operation(item))
        .collect()
}

3. Blocking in Async Contexts

Problem:

// Go goroutines can block freely:
// go func() {
//     result := expensiveComputation() // Blocking is fine
//     ch <- result
// }()

// Rust async tasks should not block:
tokio::spawn(async {
    let result = expensive_computation(); // Blocks the runtime!
    result
});

Solution:

// Use spawn_blocking for CPU-bound work:
tokio::spawn(async {
    let result = tokio::task::spawn_blocking(|| {
        expensive_computation()
    })
    .await
    .unwrap();

    result
});

4. Misusing

unwrap()

and

expect()

Problem:

// Go forces explicit error handling:
// val, err := doSomething()
// if err != nil { ... }

// Rust makes it easy to panic:
fn process() {
    let val = do_something().unwrap(); // Panics on error!
}

Solution:

// Propagate errors with ?:
fn process() -> Result<(), Error> {
    let val = do_something()?;
    Ok(())
}

// Or handle explicitly:
fn process() {
    match do_something() {
        Ok(val) => { /* use val */ },
        Err(e) => { /* handle error */ },
    }
}

5. Not Understanding String vs &str

Problem:

// Allocating strings unnecessarily:
fn greet(name: String) -> String {
    format!("Hello, {}", name)
}

let greeting = greet("World".to_string()); // Allocation

Solution:

// Use &str for parameters when not consuming:
fn greet(name: &str) -> String {
    format!("Hello, {}", name)
}

let greeting = greet("World"); // No unnecessary allocation

6. Mutex Deadlocks

Problem:

// Go: defer mu.Unlock() prevents deadlocks

// Rust: forgetting to drop lock guards
fn update(counter: &Mutex<i32>) {
    let mut count = counter.lock().unwrap();
    *count += 1;
    // count guard still held!

    let other = counter.lock().unwrap(); // Deadlock!
}

Solution:

// Drop lock guard explicitly or use scopes:
fn update(counter: &Mutex<i32>) {
    {
        let mut count = counter.lock().unwrap();
        *count += 1;
    } // count guard dropped here

    let other = counter.lock().unwrap(); // OK
}

7. Ignoring Result/Option Types

Problem:

// Compiler warns but doesn't error:
fn main() {
    do_something(); // Warning: unused Result
}

Solution:

// Handle or explicitly ignore:
fn main() {
    let _ = do_something(); // Explicitly ignore

    // Or handle:
    if let Err(e) = do_something() {
        eprintln!("Error: {}", e);
    }
}

8. Overusing Arc<Mutex<T>>

Problem:

// Wrapping everything in Arc<Mutex> because it compiles:
struct App {
    config: Arc<Mutex<Config>>,  // Config never changes!
    cache: Arc<Mutex<Cache>>,    // Could use RwLock
}

Solution:

// Use appropriate wrapper for the access pattern:
struct App {
    config: Arc<Config>,              // Read-only, no mutex needed
    cache: Arc<RwLock<Cache>>,       // Many readers, few writers
    counter: Arc<AtomicUsize>,       // Atomic operations are faster
}

Tooling

Translation and Analysis

c2rust

go2rs

Rust Ecosystem Equivalents

net/http

reqwest

net/http

axum

actix-web

encoding/json

serde_json

flag

cobra

clap

log

zap

tracing

log

testing

cargo test

testing

criterion

tokio

async-std

database/sql

sqlx

diesel

errors

thiserror

anyhow

viper

config

figment

text/template

tera

handlebars

chan

tokio::sync::mpsc

context.Context

reflect

Any

Development Tools

cargo

rustfmt

gofmt

clippy

golint

rust-analyzer

cargo-watch

cargo-expand

miri

Migration Strategy

1. Start with types: Translate struct definitions and interfaces to Rust types
2. Port tests: Convert test cases to Rust (validates correctness)
3. Translate functions: Convert Go functions to Rust, starting with pure functions
4. Handle concurrency: Replace goroutines/channels with async/await
5. Refine ownership: Optimize borrows and eliminate unnecessary clones
6. Benchmark: Compare performance and iterate

Examples

Example 1: Simple - HTTP Client Request

Before (Go):

package main

import (
    "encoding/json"
    "fmt"
    "io"
    "net/http"
)

type User struct {
    ID   int    `json:"id"`
    Name string `json:"name"`
}

func getUser(id int) (*User, error) {
    resp, err := http.Get(fmt.Sprintf("https://api.example.com/users/%d", id))
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()

    if resp.StatusCode != http.StatusOK {
        return nil, fmt.Errorf("unexpected status: %d", resp.StatusCode)
    }

    body, err := io.ReadAll(resp.Body)
    if err != nil {
        return nil, err
    }

    var user User
    if err := json.Unmarshal(body, &user); err != nil {
        return nil, err
    }

    return &user, nil
}

After (Rust):

use serde::Deserialize;
use reqwest;

#[derive(Debug, Deserialize)]
struct User {
    id: i32,
    name: String,
}

async fn get_user(id: i32) -> Result<User, reqwest::Error> {
    let url = format!("https://api.example.com/users/{}", id);

    let user = reqwest::get(&url)
        .await?
        .error_for_status()?
        .json::<User>()
        .await?;

    Ok(user)
}

Key Changes:

• async/await

  instead of blocking calls

• reqwest

  crate for ergonomic HTTP

• serde

  for type-safe JSON deserialization

• ?

  operator for error propagation
• No manual body reading (handled by

  .json()

  )

Example 2: Medium - Concurrent File Processing

Before (Go):

package main

import (
    "fmt"
    "io/ioutil"
    "os"
    "path/filepath"
    "sync"
)

type FileResult struct {
    Path  string
    Lines int
    Err   error
}

func countLines(path string) (int, error) {
    data, err := ioutil.ReadFile(path)
    if err != nil {
        return 0, err
    }

    lines := 0
    for _, b := range data {
        if b == '\n' {
            lines++
        }
    }
    return lines, nil
}

func processDirectory(dir string) ([]FileResult, error) {
    files, err := filepath.Glob(filepath.Join(dir, "*.txt"))
    if err != nil {
        return nil, err
    }

    results := make(chan FileResult, len(files))
    var wg sync.WaitGroup

    for _, file := range files {
        wg.Add(1)
        go func(path string) {
            defer wg.Done()
            lines, err := countLines(path)
            results <- FileResult{
                Path:  path,
                Lines: lines,
                Err:   err,
            }
        }(file)
    }

    go func() {
        wg.Wait()
        close(results)
    }()

    var allResults []FileResult
    for result := range results {
        allResults = append(allResults, result)
    }

    return allResults, nil
}

After (Rust):

use std::path::{Path, PathBuf};
use tokio::fs;
use tokio::task;
use glob::glob;

#[derive(Debug)]
struct FileResult {
    path: PathBuf,
    lines: usize,
    error: Option<String>,
}

async fn count_lines(path: &Path) -> Result<usize, std::io::Error> {
    let data = fs::read(path).await?;

    Ok(data.iter().filter(|&&b| b == b'\n').count())
}

async fn process_directory(dir: &Path) -> Result<Vec<FileResult>, Box<dyn std::error::Error>> {
    let pattern = dir.join("*.txt").display().to_string();
    let files: Vec<PathBuf> = glob(&pattern)?
        .filter_map(Result::ok)
        .collect();

    let handles: Vec<_> = files
        .into_iter()
        .map(|path| {
            task::spawn(async move {
                let lines_result = count_lines(&path).await;

                FileResult {
                    path: path.clone(),
                    lines: lines_result.as_ref().map(|&l| l).unwrap_or(0),
                    error: lines_result.err().map(|e| e.to_string()),
                }
            })
        })
        .collect();

    let mut all_results = Vec::new();
    for handle in handles {
        if let Ok(result) = handle.await {
            all_results.push(result);
        }
    }

    Ok(all_results)
}

// Alternative with futures::join_all:
use futures::future::join_all;

async fn process_directory_v2(dir: &Path) -> Result<Vec<FileResult>, Box<dyn std::error::Error>> {
    let pattern = dir.join("*.txt").display().to_string();
    let files: Vec<PathBuf> = glob(&pattern)?
        .filter_map(Result::ok)
        .collect();

    let futures = files.into_iter().map(|path| async move {
        let lines_result = count_lines(&path).await;

        FileResult {
            path: path.clone(),
            lines: lines_result.as_ref().map(|&l| l).unwrap_or(0),
            error: lines_result.err().map(|e| e.to_string()),
        }
    });

    Ok(join_all(futures).await)
}

Key Changes:

• tokio::task::spawn

  instead of goroutines
• Async file I/O with

  tokio::fs

• Iterator methods for concise code
• Type-safe error handling with

  Result

• No manual channel management (collect into

  Vec

  )

Example 3: Complex - Web Server with Middleware

Before (Go):

package main

import (
    "context"
    "encoding/json"
    "log"
    "net/http"
    "time"
)

type Server struct {
    db    Database
    cache Cache
}

type Database interface {
    GetUser(ctx context.Context, id string) (*User, error)
    CreateUser(ctx context.Context, user *User) error
}

type Cache interface {
    Get(key string) (interface{}, bool)
    Set(key string, value interface{}, ttl time.Duration)
}

type User struct {
    ID        string    `json:"id"`
    Email     string    `json:"email"`
    CreatedAt time.Time `json:"created_at"`
}

type CreateUserRequest struct {
    Email string `json:"email"`
}

func (s *Server) loggingMiddleware(next http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        start := time.Now()
        log.Printf("Started %s %s", r.Method, r.URL.Path)

        next(w, r)

        log.Printf("Completed in %v", time.Since(start))
    }
}

func (s *Server) getUser(w http.ResponseWriter, r *http.Request) {
    id := r.URL.Query().Get("id")
    if id == "" {
        http.Error(w, "missing id parameter", http.StatusBadRequest)
        return
    }

    // Check cache first
    if cached, ok := s.cache.Get("user:" + id); ok {
        user := cached.(*User)
        json.NewEncoder(w).Encode(user)
        return
    }

    // Fetch from database
    ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
    defer cancel()

    user, err := s.db.GetUser(ctx, id)
    if err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    // Cache the result
    s.cache.Set("user:"+id, user, 5*time.Minute)

    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(user)
}

func (s *Server) createUser(w http.ResponseWriter, r *http.Request) {
    var req CreateUserRequest
    if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
        http.Error(w, err.Error(), http.StatusBadRequest)
        return
    }

    user := &User{
        ID:        generateID(),
        Email:     req.Email,
        CreatedAt: time.Now(),
    }

    ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
    defer cancel()

    if err := s.db.CreateUser(ctx, user); err != nil {
        http.Error(w, err.Error(), http.StatusInternalServerError)
        return
    }

    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(http.StatusCreated)
    json.NewEncoder(w).Encode(user)
}

func main() {
    server := &Server{
        db:    &PostgresDB{},
        cache: &RedisCache{},
    }

    http.HandleFunc("/users", server.loggingMiddleware(server.getUser))
    http.HandleFunc("/users/create", server.loggingMiddleware(server.createUser))

    log.Fatal(http.ListenAndServe(":8080", nil))
}

func generateID() string {
    return "user-123" // Simplified
}

After (Rust):

use axum::{
    extract::{Query, State},
    http::StatusCode,
    middleware::{self, Next},
    response::{IntoResponse, Response},
    routing::{get, post},
    Json, Router,
};
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use std::time::{Duration, Instant};
use tokio::time::timeout;
use tracing::{info, instrument};

// Traits (Go interfaces)
#[async_trait::async_trait]
trait Database: Send + Sync {
    async fn get_user(&self, id: &str) -> Result<User, DatabaseError>;
    async fn create_user(&self, user: &User) -> Result<(), DatabaseError>;
}

#[async_trait::async_trait]
trait Cache: Send + Sync {
    async fn get(&self, key: &str) -> Option<User>;
    async fn set(&self, key: &str, value: User, ttl: Duration);
}

// Error types
#[derive(Debug)]
enum DatabaseError {
    NotFound,
    Internal(String),
}

#[derive(Debug, Clone, Serialize, Deserialize)]
struct User {
    id: String,
    email: String,
    created_at: chrono::DateTime<chrono::Utc>,
}

#[derive(Deserialize)]
struct CreateUserRequest {
    email: String,
}

#[derive(Deserialize)]
struct GetUserQuery {
    id: String,
}

// Shared server state
struct AppState {
    db: Arc<dyn Database>,
    cache: Arc<dyn Cache>,
}

// Logging middleware
#[instrument(skip(req, next))]
async fn logging_middleware(
    req: axum::extract::Request,
    next: Next,
) -> Response {
    let method = req.method().clone();
    let uri = req.uri().clone();
    let start = Instant::now();

    info!("Started {} {}", method, uri);

    let response = next.run(req).await;

    info!("Completed in {:?}", start.elapsed());

    response
}

// Handlers
#[instrument(skip(state))]
async fn get_user(
    Query(params): Query<GetUserQuery>,
    State(state): State<Arc<AppState>>,
) -> Result<Json<User>, AppError> {
    let cache_key = format!("user:{}", params.id);

    // Check cache first
    if let Some(user) = state.cache.get(&cache_key).await {
        return Ok(Json(user));
    }

    // Fetch from database with timeout
    let user = timeout(
        Duration::from_secs(5),
        state.db.get_user(&params.id)
    )
    .await
    .map_err(|_| AppError::Timeout)?
    .map_err(AppError::Database)?;

    // Cache the result
    state.cache.set(&cache_key, user.clone(), Duration::from_secs(300)).await;

    Ok(Json(user))
}

#[instrument(skip(state))]
async fn create_user(
    State(state): State<Arc<AppState>>,
    Json(req): Json<CreateUserRequest>,
) -> Result<(StatusCode, Json<User>), AppError> {
    let user = User {
        id: generate_id(),
        email: req.email,
        created_at: chrono::Utc::now(),
    };

    // Create user with timeout
    timeout(
        Duration::from_secs(5),
        state.db.create_user(&user)
    )
    .await
    .map_err(|_| AppError::Timeout)?
    .map_err(AppError::Database)?;

    Ok((StatusCode::CREATED, Json(user)))
}

// Error handling
enum AppError {
    Database(DatabaseError),
    Timeout,
}

impl IntoResponse for AppError {
    fn into_response(self) -> Response {
        let (status, message) = match self {
            AppError::Database(DatabaseError::NotFound) => {
                (StatusCode::NOT_FOUND, "User not found")
            }
            AppError::Database(DatabaseError::Internal(msg)) => {
                (StatusCode::INTERNAL_SERVER_ERROR, "Internal error")
            }
            AppError::Timeout => {
                (StatusCode::REQUEST_TIMEOUT, "Request timeout")
            }
        };

        (status, message).into_response()
    }
}

fn generate_id() -> String {
    "user-123".to_string() // Simplified
}

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt::init();

    let state = Arc::new(AppState {
        db: Arc::new(PostgresDB::new()),
        cache: Arc::new(RedisCache::new()),
    });

    let app = Router::new()
        .route("/users", get(get_user))
        .route("/users/create", post(create_user))
        .layer(middleware::from_fn(logging_middleware))
        .with_state(state);

    let listener = tokio::net::TcpListener::bind("0.0.0.0:8080")
        .await
        .unwrap();

    info!("Server listening on {}", listener.local_addr().unwrap());

    axum::serve(listener, app).await.unwrap();
}

// Placeholder implementations
struct PostgresDB;
impl PostgresDB {
    fn new() -> Self { PostgresDB }
}

#[async_trait::async_trait]
impl Database for PostgresDB {
    async fn get_user(&self, id: &str) -> Result<User, DatabaseError> {
        // Implementation
        todo!()
    }

    async fn create_user(&self, user: &User) -> Result<(), DatabaseError> {
        // Implementation
        todo!()
    }
}

struct RedisCache;
impl RedisCache {
    fn new() -> Self { RedisCache }
}

#[async_trait::async_trait]
impl Cache for RedisCache {
    async fn get(&self, key: &str) -> Option<User> {
        // Implementation
        None
    }

    async fn set(&self, key: &str, value: User, ttl: Duration) {
        // Implementation
    }
}

Key Changes:

• axum

  framework for type-safe routing
• Middleware as async functions
• Traits with

  async_trait

  for interfaces
• State sharing via

  Arc<AppState>

• Structured error handling with

  IntoResponse

• tracing

  for structured logging
• Type-safe extractors (

  Query

  ,

  Json

  ,

  State

  )
• Explicit timeout handling
• Clone for cache storage (explicit copying)

See Also

For more examples and patterns, see:

• meta-convert-dev

  - Foundational patterns with cross-language examples

• lang-go-dev

  - Go development patterns

• lang-rust-dev

  - Rust development patterns

• lang-rust-library-dev

  - Rust library-specific patterns

• lang-rust-memory-eng

  - Advanced Rust memory management