How to handle errors when using lo.Map in Go?

Use MapErr which returns an error alongside the transformed slice. For example, lo.MapErr can catch errors from the transform function, ensuring safe data processing without panics, as shown in the README code snippets.

Lo vs Go's built-in slices package: which is better?

Lo offers more advanced utilities like GroupBy, Parallel processing, and error handling, but for basic operations, Go's slices package might be sufficient. Choose Lo if you need Lodash-style expressiveness with generics.

Does lo support parallel execution for collection operations?

Yes, via the lo/parallel package. Functions like lop.Map run transform functions in goroutines while preserving order, making it useful for CPU-bound tasks, as demonstrated in the parallel processing examples.

How to convert a string to camel case using lo?

Use lo.CamelCase function. For instance, lo.CamelCase('hello_world') returns 'helloWorld'. It handles various string transformations efficiently, including case conversions and truncation.

What is the performance impact of using lo in Go apps?

Lo adds minimal overhead due to generics and no external dependencies, but for tight loops, inline code might be faster. The parallel package can improve performance for concurrent tasks by leveraging goroutines.

Can I use lo with Go modules and what about versioning?

Yes, install with 'go get github.com/samber/lo@v1'. It follows SemVer strictly, with no breaking changes until v2.0.0, except for experimental packages under exp/, ensuring stability for production use.

lo — Lodash-Style Go Utility Library

What is lo?

Lo is a comprehensive utility library for Go that provides dozens of synchronous helper functions for manipulating slices, maps, strings, channels, and functions. Inspired by Lodash, it leverages Go 1.18+ generics to offer type-safe operations that simplify common coding tasks and improve code readability. It focuses on synchronous helpers for finite sequences while maintaining zero dependencies outside the Go standard library.

Target Audience

Go developers working with Go 1.18+ who need expressive, type-safe utilities for data manipulation, particularly those familiar with Lodash-style functional programming patterns. It's especially useful for developers handling collections, concurrency patterns, and string transformations in their applications.

Value Proposition

Developers choose Lo for its extensive collection of type-safe, generic utilities that bring Lodash-like expressiveness to Go, combined with zero external dependencies. Its unique selling point is providing dozens of synchronous helpers across multiple data types (slices, maps, strings, channels) with full generics support, plus specialized packages for parallel processing, mutable operations, and iteration.

💥 A Lodash-style Go library based on Go 1.18+ Generics (map, filter, contains, find...)

Use Cases

Best For

Transforming and querying collections with functional operations like Map, Filter, Reduce, and GroupBy
Implementing concurrency patterns with utilities like ChannelDispatcher, FanIn, FanOut, and parallel processing variants
Manipulating strings with case conversion (CamelCase, SnakeCase), truncation, chunking, and word splitting
Handling errors in collection operations with integrated error propagation in functions like MapErr, FilterErr, and Try
Working with tuples and zipping multiple collections together using T2-T9, Zip2-Zip9, and related helpers
Performing mathematical operations on collections with Sum, Product, Mean, Mode, and Range functions

Not Ideal For

Projects stuck on Go versions below 1.18 due to its reliance on generics
Applications processing infinite data streams or event-driven architectures better served by reactive libraries like samber/ro
Codebases needing only basic slice/map operations where Go's standard slices and maps packages suffice
Environments where minimizing code bulk is critical, as Lo adds hundreds of functions even with zero dependencies

Pros & Cons

Pros

Type-Safe Generics Support

Leverages Go 1.18+ generics for compile-time type checking across all operations, ensuring safety and reducing runtime errors, as evidenced by functions like Map and Filter that work with any type.

Comprehensive Error Handling

Integrates error propagation directly into collection functions like MapErr and FilterErr, allowing robust operations without breaking the functional programming flow, which is detailed in the README examples.

Concurrency and Parallel Utilities

Includes helpers such as ChannelDispatcher, FanIn, and parallel processing variants in the lo/parallel package, facilitating goroutine-safe operations and efficient data processing for concurrent scenarios.

Zero External Dependencies

Maintains no dependencies outside the Go standard library, simplifying integration and reducing dependency management overhead, as stated in the installation and philosophy sections.

Cons

Redundancy with Standard Library

The README admits that 5-10 helpers overlap with Go's slices and maps packages, which can lead to confusion or unnecessary code duplication for developers already using standard library functions.

Mutable Operations Risks

Functions in lo/mutable, like Shuffle and Reverse, modify slices in place, increasing the risk of unintended side effects and bugs if not handled carefully, as highlighted in the mutable examples.

Steep API Learning Curve

With over a hundred functions across slices, maps, strings, and more, the extensive API can be overwhelming for newcomers and may introduce complexity in projects that only need a subset of features.

Frequently Asked Questions

What is lo?

Target Audience

Value Proposition

Use Cases

Best For

Transforming and querying collections with functional operations like Map, Filter, Reduce, and GroupBy
Implementing concurrency patterns with utilities like ChannelDispatcher, FanIn, FanOut, and parallel processing variants
Manipulating strings with case conversion (CamelCase, SnakeCase), truncation, chunking, and word splitting
Handling errors in collection operations with integrated error propagation in functions like MapErr, FilterErr, and Try
Working with tuples and zipping multiple collections together using T2-T9, Zip2-Zip9, and related helpers
Performing mathematical operations on collections with Sum, Product, Mean, Mode, and Range functions

Not Ideal For

Projects stuck on Go versions below 1.18 due to its reliance on generics
Applications processing infinite data streams or event-driven architectures better served by reactive libraries like samber/ro
Codebases needing only basic slice/map operations where Go's standard slices and maps packages suffice
Environments where minimizing code bulk is critical, as Lo adds hundreds of functions even with zero dependencies

Pros & Cons

Pros

Type-Safe Generics Support

Leverages Go 1.18+ generics for compile-time type checking across all operations, ensuring safety and reducing runtime errors, as evidenced by functions like Map and Filter that work with any type.

Comprehensive Error Handling

Concurrency and Parallel Utilities

Zero External Dependencies

Maintains no dependencies outside the Go standard library, simplifying integration and reducing dependency management overhead, as stated in the installation and philosophy sections.

Cons

Redundancy with Standard Library

The README admits that 5-10 helpers overlap with Go's slices and maps packages, which can lead to confusion or unnecessary code duplication for developers already using standard library functions.

Mutable Operations Risks

Functions in lo/mutable, like Shuffle and Reverse, modify slices in place, increasing the risk of unintended side effects and bugs if not handled carefully, as highlighted in the mutable examples.

Steep API Learning Curve

With over a hundred functions across slices, maps, strings, and more, the extensive API can be overwhelming for newcomers and may introduce complexity in projects that only need a subset of features.

Frequently Asked Questions

lo

What is lo?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Open Source Alternative To

Frequently Asked Questions

Related Projects

Found a gem we're missing?

lo

What is lo?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Open Source Alternative To

Frequently Asked Questions

Related Projects

Found a gem we're missing?