go2linq

A powerful language integrated query (LINQ) library for Go.

• Safe for concurrent use
• Complete lazy evaluation
• Supports arrays, slices, maps, strings, channels and
  custom collections (collection needs to implement Iterable interface
  and element - Comparable interface)
• Parallel LINQ (PLINQ) (comming soon)

⚠️ ⚠️ go2linq has been merged into the go-linqs master branch. Now it is available as the newest version of go-linq library (v2.0.0).

All further development will be conducted in the new location and this repository will remain only for compatibility reasons. Please, do not use it anymore!

Installation

$ go get github.com/kalaninja/go2linq

Quickstart

Usage is as easy as chaining methods like

From(slice) .Where(predicate) .Select(selector) .Union(data)

Just keep writing.

Example: Find all owners of cars manufactured from 2015

import . "github.com/kalaninja/go2linq"
	
type Car struct {
    id, year int
    owner, model string
}

owners := []string{}

From(cars).Where(func(c interface{}) bool {
	return c.(Car).year >= 2015
}).Select(func(c interface{}) interface{} {
	return c.(Car).owner
}).ToSlice(&owners)

Example: Find an author that has written the most books

import . "github.com/kalaninja/go2linq"
	
type Book struct {
	id      int
	title   string
	authors []string
}

author := From(books).SelectMany(func(b interface{}) Query {
		return From(b.(Book).authors)
	}).GroupBy(func(a interface{}) interface{} {
		return a
	}, func(a interface{}) interface{} {
		return a
	}).OrderByDescending(func(g interface{}) interface{} {
		return len(g.(Group).Group)
	}).Select(func(g interface{}) interface{} {
		return g.(Group).Key
	}).First()

More examples can be found in documentation

Performance

Due to lazy execution go2linq has better performance and allocates less memory in most cases. Benchmark comparing go2linq to go-linq is available in benchmark_test.go. Below is the result of this benchmark on my machine (MacBookPro8,1 Intel Core i5 2,4 GHz):

BenchmarkSelectWhereFirst-4       	 3000000	       561 ns/op	     224 B/op	      10 allocs/op
BenchmarkSelectWhereFirst_golinq-4	       2	 555810859 ns/op	120546360 B/op	 2000085 allocs/op
BenchmarkSum-4                    	      20	  73847428 ns/op	 8000289 B/op	 1000019 allocs/op
BenchmarkSum_golinq-4             	       5	 253731714 ns/op	69161392 B/op	 1000053 allocs/op
BenchmarkZipSkipTake-4            	 5000000	       351 ns/op	     192 B/op	       6 allocs/op
BenchmarkZipSkipTake_golinq-4     	       2	 672403213 ns/op	144520824 B/op	 3000075 allocs/op