convert-golang-rust

name	convert-golang-rust
description	Convert Go code to idiomatic Rust. Use when migrating Go projects to Rust, translating Go patterns to idiomatic Rust, or refactoring Go codebases. Extends meta-convert-dev with Go-to-Rust specific patterns.

Convert Go to Rust

Convert Go code to idiomatic Rust. This skill extends meta-convert-dev with Go-to-Rust specific type mappings, idiom translations, and tooling.

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

Go	Rust	Notes
string	String / &str	Owned vs borrowed
int	i32 / i64	Specify size explicitly
uint	u32 / u64	Unsigned variants
float64	f64	Direct mapping
bool	bool	Direct mapping
[]T	Vec<T>	Owned slice
[N]T	[T; N]	Fixed-size array
map[K]V	HashMap<K, V>	Hash table
chan T	mpsc::Sender<T> / Receiver<T>	Channels
interface{}	Generic with trait bounds	Type-safe alternatives
nil	None in Option<T>	Explicit nullability
error	Result<T, E>	Type-safe errors
struct	struct	Similar syntax
interface	trait	Behavioral contracts
defer	RAII / Drop trait	Automatic cleanup

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

Go	Rust	Notes
bool	bool	Direct mapping
string	String	Owned, heap-allocated UTF-8
string (param)	&str	Borrowed string slice for parameters
int	isize	Platform-dependent signed integer
int8	i8	8-bit signed
int16	i16	16-bit signed
int32 / rune	i32	32-bit signed
int64	i64	64-bit signed
uint	usize	Platform-dependent unsigned
uint8 / byte	u8	8-bit unsigned
uint16	u16	16-bit unsigned
uint32	u32	32-bit unsigned
uint64	u64	64-bit unsigned
float32	f32	32-bit float
float64	f64	64-bit float
complex64	-	Use external crate (num-complex)
complex128	-	Use external crate (num-complex)

Collection Types

Go	Rust	Notes
[]T	Vec<T>	Growable, owned array
[]T (param)	&[T]	Borrowed slice for parameters
[N]T	[T; N]	Fixed-size array on stack
map[K]V	HashMap<K, V>	Hash table, K must be Hash + Eq
map[K]V (ordered)	BTreeMap<K, V>	Ordered map, K must be Ord
Set (manual)	HashSet<T>	Deduplicated collection
Set (ordered)	BTreeSet<T>	Ordered deduplicated collection

Composite Types

Go	Rust	Notes
struct { ... }	struct { ... }	Similar syntax, explicit visibility
*T	Box<T>	Heap allocation, single owner
*T (shared)	Rc<T> / Arc<T>	Reference counted (single/multi-threaded)
interface { ... }	trait Trait { ... }	Behavior definition
struct + methods	impl Block	Method implementation
func(T) U	fn(T) -> U	Function type
func(T) U (closure)	Fn(T) -> U	Closure trait
chan T	mpsc::Sender<T>	Channel sender
<-chan T	mpsc::Receiver<T>	Channel receiver
chan<- T	mpsc::Sender<T>	Send-only channel

Pointer and Reference Types

Go	Rust	Notes
*T (nullable)	Option<Box<T>>	Nullable heap pointer
*T (non-null)	Box<T>	Non-null owned heap pointer
&T (for mutation)	&mut T	Exclusive mutable reference
Pointer to slice	&[T]	Slice reference
Pointer to map	&HashMap<K, V>	Map reference

---

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 interface and multiple return values translate to Rust's Result<T, E> enum.

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

Go Pattern	Rust Pattern	Notes
if err != nil { return nil, err }	? operator	Automatic propagation
fmt.Errorf("context: %w", err)	map_err(|e| ...)	Add context
Multiple error types	enum with #[from]	Type-safe error conversion
errors.Is(err, target)	match on error type	Pattern matching
errors.As(err, &target)	downcast_ref (rare)	Usually use enums instead
Sentinel errors	Unit variants in enum	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

Go	Rust	Notes
sync.Mutex	std::sync::Mutex	Blocking mutex
sync.RWMutex	std::sync::RwLock	Reader-writer lock
sync.WaitGroup	Manual with channels or JoinHandle	No direct equivalent
sync.Once	std::sync::Once	One-time initialization
sync.Cond	std::sync::Condvar	Condition variable
atomic.*	std::sync::atomic::*	Atomic operations
chan T	tokio::sync::mpsc	Async channels
chan T (sync)	std::sync::mpsc	Blocking channels

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>

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

Tool	Purpose	Notes
c2rust	C to Rust transpiler	Produces unsafe Rust, needs manual cleanup
go2rs	Experimental Go→Rust	Very limited, not production-ready
Manual translation	Most reliable	Use this skill as guide

Rust Ecosystem Equivalents

Category	Go	Rust	Notes
HTTP Client	net/http	reqwest	Async-first
HTTP Server	net/http	axum, actix-web	Framework-based
JSON	encoding/json	serde_json	Type-safe serialization
CLI Parsing	flag, cobra	clap	Derive-based API
Logging	log, zap	tracing, log	Structured logging
Testing	testing	Built-in cargo test	Similar experience
Benchmarking	testing	criterion	Statistical analysis
Async Runtime	Built-in goroutines	tokio, async-std	Explicit runtime
Database	database/sql	sqlx, diesel	Type-safe queries
Error Handling	errors	thiserror, anyhow	Rich error types
Configuration	viper	config, figment	Type-safe configs
Templates	text/template	tera, handlebars	Compile-time checks
Channels	chan	tokio::sync::mpsc	Async-aware
Context

Development Tools

Tool	Purpose
cargo	Build system and package manager
rustfmt	Code formatter (like gofmt)
clippy	Linter (more strict than golint)
rust-analyzer	LSP server for IDE support
cargo-watch	Auto-recompile on file changes
cargo-expand	Expand macros for debugging
miri	Detect undefined behavior

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