return nil
})
// false

ok := lo.Try(func() error {
    return nil
})
// true

ok := lo.Try(func() error {
    return errors.New("error")
})
// false
```

[[play](https://go.dev/play/p/mTyyWUvn9u4)]

### Try{0->6}

The same behavior as `Try`, but the callback returns 2 variables.

```go
ok := lo.Try2(func() (string, error) {
    panic("error")
    return "", nil
})
// false
```

[[play](https://go.dev/play/p/mTyyWUvn9u4)]

### TryOr

Calls the function and return a default value in case of error and on panic.

```go
str, ok := lo.TryOr(func() (string, error) {
    panic("error")
    return "hello", nil
}, "world")
// world
// false

str, ok := lo.TryOr(func() error {
    return "hello", nil
}, "world")
// hello
// true

str, ok := lo.TryOr(func() error {
    return "hello", errors.New("error")
}, "world")
// world
// false
```

[[play](https://go.dev/play/p/B4F7Wg2Zh9X)]

### TryOr{0->6}

The same behavior as `TryOr`, but the callback returns `X` variables.

```go
str, nbr, ok := lo.TryOr2(func() (string, int, error) {
    panic("error")
    return "hello", 42, nil
}, "world", 21)
// world
// 21
// false
```

[[play](https://go.dev/play/p/B4F7Wg2Zh9X)]

### TryWithErrorValue

The same behavior as `Try`, but also returns the value passed to panic.

```go
err, ok := lo.TryWithErrorValue(func() error {
    panic("error")
    return nil
})
// "error", false
```

[[play](https://go.dev/play/p/Kc7afQIT2Fs)]

### TryCatch

The same behavior as `Try`, but calls the catch function in case of error.

```go
caught := false

ok := lo.TryCatch(func() error {
    panic("error")
    return nil
}, func() {
    caught = true
})
// false
// caught == true
```

[[play](https://go.dev/play/p/PnOON-EqBiU)]

### TryCatchWithErrorValue

The same behavior as `TryWithErrorValue`, but calls the catch function in case of error.

```go
caught := false

ok := lo.TryCatchWithErrorValue(func() error {
    panic("error")
    return nil
}, func(val any) {
    caught = val == "error"
})
// false
// caught == true
```

[[play](https://go.dev/play/p/8Pc9gwX_GZO)]

### ErrorsAs

A shortcut for:

```go
err := doSomething()

var rateLimitErr *RateLimitError
if ok := errors.As(err, &rateLimitErr); ok {
    // retry later
}
```

single line `lo` helper:

```go
err := doSomething()

if rateLimitErr, ok := lo.ErrorsAs[*RateLimitError](err); ok {
    // retry later
}
```

[[play](https://go.dev/play/p/8wk5rH8UfrE)]

### Assert

Does nothing when the condition is `true`, otherwise it panics with an optional message.

Think twice before using it, given that [Go intentionally omits assertions from its standard library](https://go.dev/doc/faq#assertions).

```go
age := getUserAge()

lo.Assert(age >= 15)
```

```go
age := getUserAge()

lo.Assert(age >= 15, "user age must be >= 15")
```

[[play](https://go.dev/play/p/Xv8LLKBMNwI)]

### Assertf

Like `Assert`, but with `fmt.Printf`-like formatting.

Think twice before using it, given that [Go intentionally omits assertions from its standard library](https://go.dev/doc/faq#assertions).

```go
age := getUserAge()

lo.Assertf(age >= 15, "user age must be >= 15, got %d", age)
```

[[play](https://go.dev/play/p/TVPEmVcyrdY)]

## 🛩 Benchmark

We executed a simple benchmark with a dead-simple `lo.Map` loop:

See the full implementation [here](./map_benchmark_test.go).

```go
_ = lo.Map[int64](arr, func(x int64, i int) string {
    return strconv.FormatInt(x, 10)
})
```

**Result:**

Here is a comparison between `lo.Map`, `lop.Map`, `go-funk` library and a simple Go `for` loop.

```shell
$ go test -benchmem -bench ./...
goos: linux
goarch: amd64
pkg: github.com/samber/lo
cpu: Intel(R) Core(TM) i5-7267U CPU @ 3.10GHz
cpu: Intel(R) Core(TM) i7 CPU         920  @ 2.67GHz
BenchmarkMap/lo.Map-8         	       8	 132728237 ns/op	39998945 B/op	 1000002 allocs/op
BenchmarkMap/lop.Map-8        	       2	 503947830 ns/op	119999956 B/op	 3000007 allocs/op
BenchmarkMap/reflect-8        	       2	 826400560 ns/op	170326512 B/op	 4000042 allocs/op
BenchmarkMap/for-8            	       9	 126252954 ns/op	39998674 B/op	 1000001 allocs/op
PASS
ok  	github.com/samber/lo	6.657s
```

- `lo.Map` is way faster (x7) than `go-funk`, a reflection-based Map implementation.
- `lo.Map` has the same allocation profile as `for`.
- `lo.Map` is 4% slower than `for`.
- `lop.Map` is slower than `lo.Map` because it implies more memory allocation and locks. `lop.Map` is useful for long-running callbacks, such as i/o bound processing.
- `for` beats other implementations for memory and CPU.

## 🤝 Contributing

- Ping me on Twitter [@samuelberthe](https://twitter.com/samuelberthe) (DMs, mentions, whatever :))
- Fork the [project](https://github.com/samber/lo)
- Fix [open issues](https://github.com/samber/lo/issues) or request new features

Don't hesitate ;)

Helper naming: helpers must be self-explanatory and respect standards (other languages, libraries...). Feel free to suggest many names in your contributions.

```bash
# Install some dev dependencies
make tools

# Run tests
make test
# or
make watch-test
```

## 👤 Contributors

![Contributors](https://contrib.rocks/image?repo=samber/lo)

## 💫 Show your support

Give a ⭐️ if this project helped you!

[![GitHub Sponsors](https://img.shields.io/github/sponsors/samber?style=for-the-badge)](https://github.com/sponsors/samber)

## 📝 License

Copyright © 2022 [Samuel Berthe](https://github.com/samber).

This project is under [MIT](./LICENSE) license.