Godash
Inspired from Lodash for golang
Why?
- I did not like most map/reduce implementations that returned an
interface{}which had to be typecasted. This library follows the concept of howjson.Marshalworks. Create an output variable outside the functions and pass a pointer reference to it, so it can be set. - This library heavily makes use of
reflectpackage and hence will have an impact on performance. DO NOT USE THIS IN PRODUCTION. This repository is more of a way to learn the reflect package and measure its performance impact. - All functions have validations on how mapper function/predicate functions should be written. So even if we lose out on compile time validation, the library still does not panic if it does not know how to handle an argument passed to it.
Available Functions
Usages
Map
Map applies a mapper function on each element of an input and sets it in output. For more docs.
func main() {
input := []int{1, 2, 3, 4, 5}
var output []int
godash.Map(input, &output, func(el int) int {
return el * el
})
fmt.Println(output) // prints 1 4 9 16 25
}type Person struct {
Name string
Age Int
}
func main() {
input := []Person{
{Name: "John", Age: 22},
{Name: "Doe", Age: 23},
}
var output []string
godash.Map(input, &output, func(person Person) string {
return person.Name
})
fmt.Println(output) // prints John Doe
}func main() {
input := map[string]int{
"key1": 1,
"key2": 2,
"key3": 3,
}
var output []int
godash.Map(input, &output, func(el int) int {
return el * el
})
fmt.Println(output) // prints 1 4 9
}Filter
Filter out elements that fail the predicate. For more docs.
func main() {
input := []int{1, 2, 3, 4, 5}
var output []int
godash.Filter(input, &output, func(element int) bool {
return element % 2 == 0
})
fmt.Println(output) // prints 2 4
}func main() {
input := []Person{
{Name: "John", Age: 20},
{Name: "Doe", Age: 30},
}
var output []string
godash.Filter(input, &output, func(person Person) bool {
return person.Age > 25
})
fmt.Println(output) // prints {Doe 30}
}Reduce
Reduce can accept a reducer and apply the reducer on each element of the input slice while providing an accumulator to save the reduce output. For more docs.
func main() {
input := []string{"count", "words", "and", "print", "words", "count"}
accumulator := map[string]int{}
_ = godash.Reduce(input, &accumulator, func(acc map[string]int, element string) map[string]int {
if _, present := acc[element]; present {
acc[element] = acc[element] + 1
} else {
acc[element] = 1
}
return acc
})
bytes, _ := json.MarshalIndent(accumulator, "", " ")
fmt.Println(string(bytes))
// Output:
//{
// "and": 1,
// "count": 2,
// "print": 1,
// "words": 2
//}
}func main() {
input := []Person{
{Name: "John", Age: 22},
{Name: "Doe", Age: 23},
}
var output int
godash.Reduce(input, &output, func(sum int, person Person) int {
return sum + person.Age
})
fmt.Println(output) // prints 45
}Any or Some
Any or Some checks if predicate returns truthy for any element of collection. Iteration is stopped once predicate returns truthy. For more docs.
func main() {
input := []int{1, 2, 3, 4, 5}
var output []int
output, _ := godash.Any(input, func(num int) bool {
return num % 7 == 0
})
fmt.Println(output) // prints false
}func main() {
input := []Person{
{Name: "John", Age: 25},
{Name: "Doe", Age: 15},
}
var output int
output, _ := godash.Some(input, func(person Person) bool {
return person.Age < 18
})
fmt.Println(output) // prints true
}Find
Returns the first element which passes the predicate. For more docs.
func main() {
input := []string{"john","wick","will"}
var output string
godash.Find(input, &output, func(element string) bool {
return strings.HasPrefix(element, "w") // starts with
}
// output is "wick"
fmt.Println(output)
}All or Every
All or Every checks if predicate returns truthy for all element of collection. Iteration is stopped once predicate returns falsely. For more docs.
func main() {
input := []int{1, 2, 3, 4, 5}
var output bool
output, _ := godash.All(input, func(num int) bool {
return num >= 1
})
fmt.Println(output) // prints true
} func main() {
input := []Person{
{Name: "John", Age: 25},
{Name: "Doe", Age: 15},
}
var output bool
output, _ := godash.Every(input, func(person Person) bool {
return person.Age < 18
})
fmt.Println(output) // prints false
}