Go Equivalent for Python's List Comprehension

Python's list comprehension offers a concise way to generate lists by filtering and transforming elements. However, if you're transitioning to Go and find it challenging to replicate this functionality, here's a solution:

Elegant Solution Using filter Package

Thankfully, the Go community has provided the filter package, which offers functionality similar to Python's list comprehension. Specifically, its Choose function takes a slice and a filtering function, returning a new slice containing only the elements that pass the filter.

import "github.com/rogpeppe/go-internal/filter"

func Choose(slice []T, fn func(T) bool) []T

Example:

// Get even numbers from a list
a := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}
expect := []int{2, 4, 6, 8}
result := filter.Choose(a, isEven)

Alternative Approach: For Loops

While the filter package provides convenience, it's important to note that using traditional for loops is still a viable and efficient option. Go's for loops offer flexibility and optimization opportunities.

for i := range a {
    if someCondition {
        result = append(result, a[i])
    }
}

Conclusion

Despite the lack of native list comprehension syntax in Go, the filter package and for loops offer robust solutions for filtering and transforming lists. While the filter package provides a concise syntax, for loops remain a performant and efficient alternative. Ultimately, the choice of approach will depend on the specific requirements of your application.