Lazy like a koala, smart like a chimpanzee
Koazee is a StreamLike, Immutable, Lazy Loading and smart Golang Library to deal with slices.
Visit the Koazee wiki to find out what Koazee can do.
- Immutable: Koazee won't modify your inputs.
- StreamLike: We can combine operations up our convenience.
- Lazy loading: Operations are not performed until they're required
- Generic: Koazee provides a generic interface able to deal with slice of any type without creating custom functions.
- Focusing on performance: First rule for implementing a new operation is providing the best possible performance.
Add Koazee to your project
Go modules
module github.com/me/project
require (
github.com/wesovilabs/koazee vX.Y.Z
)
Glide
glide get github.com/wesovilabs/koazee
Go dep
go get github.com/wesovilabs/koazee
Let's first obtain a stream from an existing array.
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
var numbers = []int{1, 5, 4, 3, 2, 7, 1, 8, 2, 3}
func main() {
fmt.Printf("slice: %v\n", numbers)
stream := koazee.StreamOf(numbers)
fmt.Printf("stream: %v\n", stream.Out().Val())
}
/**
go run main.go
slice: [1 5 4 3 2 7 1 8 2 3]
stream: [1 5 4 3 2 7 1 8 2 3]
*/Current release v0.0.3 (Gibbon) brings us 20 generic operations that are showed below
These operations return an element from the stream
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
var numbers = []int{1, 5, 4, 3, 2, 7, 1, 8, 2, 3}
func main() {
stream := koazee.StreamOf(numbers)
fmt.Printf("stream.At(4): %d\n", stream.At(4).Int())
fmt.Printf("stream.First: %d\n", stream.First().Int())
fmt.Printf("stream.Last: %d\n", stream.Last().Int())
}
/**
go run main.go
stream.At(4): 2
stream.First: 1
stream.Last: 3
*/These operations add or delete elements from the stream.
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
var numbers = []int{1, 5, 4, 3, 2, 7, 1, 8, 2, 3}
func main() {
fmt.Printf("input: %v\n", numbers)
stream := koazee.StreamOf(numbers)
fmt.Print("stream.Add(10): ")
fmt.Println(stream.Add(10).Do().Out().Val())
fmt.Print("stream.Drop(5): ")
fmt.Println(stream.Drop(5).Do().Out().Val())
fmt.Print("stream.DropWhile(val<=5): ")
fmt.Println(stream.DropWhile(func(element int)bool{return element<=5}).Do().Out().Val())
fmt.Print("stream.DeleteAt(4): ")
fmt.Println(stream.DeleteAt(4).Do().Out().Val())
fmt.Print("stream.Set(0,5): ")
fmt.Println(stream.Set(0, 5).Do().Out().Val())
fmt.Print("stream.Pop(): ")
val, newStream := stream.Pop()
fmt.Printf("%d ... ", val.Int())
fmt.Println(newStream.Out().Val())
}
/**
go run main.go
input: [1 5 4 3 2 7 1 8 2 3]
stream.Add(10): [1 5 4 3 2 7 1 8 2 3 10]
stream.Drop(5): [1 4 3 2 7 1 8 2 3]
stream.DropWhile(val<=5): [7 8]
stream.DeleteAt(4): [1 5 4 3 7 1 8 2 3]
stream.Set(0,5): [5 5 4 3 2 7 1 8 2 3]
stream.Pop(): 1 ... [5 4 3 2 7 1 8 2 3]
*/These operations return info from the elements in the stream
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
var numbers = []int{1, 5, 4, 3, 2, 7, 1, 8, 2, 3}
func main() {
fmt.Printf("input: %v\n", numbers)
stream := koazee.StreamOf(numbers)
count, _ := stream.Count()
fmt.Printf("stream.Count(): %d\n", count)
index, _ := stream.IndexOf(2)
fmt.Printf("stream.IndexOf(2): %d\n", index)
indexes, _ := stream.IndexesOf(2)
fmt.Printf("stream.IndexesOf(2): %d\n", indexes)
index, _ = stream.LastIndexOf(2)
fmt.Printf("stream.LastIndexOf(2): %d\n", index)
contains, _ := stream.Contains(7)
fmt.Printf("stream.Contains(7): %v\n", contains)
}
/**
go run main.go
input: [1 5 4 3 2 7 1 8 2 3]
stream.Count(): 10
stream.IndexOf(2): 4
stream.IndexesOf(2): [4 8]
stream.LastIndexOf(2): 8
stream.Contains(7): true
*/These operations organize the elements in the stream.
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
"strings"
)
var animals = []string{"lynx", "dog", "cat", "monkey", "fox", "tiger", "lion"}
func main() {
fmt.Print("input: ")
fmt.Println(animals)
stream := koazee.StreamOf(animals)
fmt.Print("stream.Reverse(): ")
fmt.Println(stream.Reverse().Out().Val())
fmt.Print("stream.Sort(strings.Compare): ")
fmt.Println(stream.Sort(strings.Compare).Out().Val())
}
/**
go run main.go
input: [lynx dog cat monkey fox tiger lion]
stream.Reverse(): [lion tiger fox monkey cat dog lynx]
stream.Sort(strings.Compare): [cat dog fox lion lynx monkey tiger]
*/These operations return a filtered stream.
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
var animals = []string{"lynx", "dog", "cat", "monkey", "dog", "fox", "tiger", "lion"}
func main() {
fmt.Print("input: ")
fmt.Println(animals)
stream := koazee.StreamOf(animals)
fmt.Print("stream.Take(1,4): ")
fmt.Println(stream.Take(1, 4).Out().Val())
fmt.Print("stream.Filter(len==4): ")
fmt.Println(stream.
Filter(
func(val string) bool {
return len(val) == 4
}).
Out().Val(),
)
fmt.Print("stream.RemoveDuplicates(): ")
fmt.Println(stream.RemoveDuplicates().Out().Val())
}
/**
go run main.go
input: [lynx dog cat monkey dog fox tiger lion]
stream.Take(1,4): [dog cat monkey dog]
stream.Filter(len==4): [lynx lion]
stream.RemoveDuplicates(): [lynx dog cat monkey fox tiger lion]
*/This operation creates groups depending on the returned function value
You can now optionally return an error as the second parameter to stop processing of the stream. The error will be available in stream.Out().Err().UserError().
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
"strings"
)
var animals = []string{"lynx", "dog", "cat", "monkey", "dog", "fox", "tiger", "lion"}
func main() {
fmt.Printf("input: %v\n", animals)
stream := koazee.StreamOf(animals)
fmt.Print("stream.GroupBy(strings.Len): ")
out, _ := stream.GroupBy(func(val string)int{return len(val)})
fmt.Println(out)
}
/**
go run main.go
input: [lynx dog cat monkey dog fox tiger lion]
stream.GroupBy(strings.Len): map[5:[tiger] 4:[lynx lion] 3:[dog cat dog fox] 6:[monkey]]
*/This operation performs a modification over all the elements in the stream.
You can now optionally return an error as the second parameter to stop processing of the stream. The error will be available in stream.Out().Err().UserError().
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
"strings"
)
var animals = []string{"lynx", "dog", "cat", "monkey", "dog", "fox", "tiger", "lion"}
func main() {
fmt.Printf("input: %v\n", animals)
stream := koazee.StreamOf(animals)
fmt.Print("stream.Map(strings.Title): ")
fmt.Println(stream.Map(strings.Title).Do().Out().Val())
}
/**
go run main.go
input: [lynx dog cat monkey dog fox tiger lion]
stream.Map(strings.Title): [Lynx Dog Cat Monkey Dog Fox Tiger Lion]
*/This operation give us a single output after iterating over the elements in the stream.
You can now optionally return an error as the second parameter to stop processing of the stream. The error will be available in stream.Out().Err().UserError().
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
var numbers = []int{1, 5, 4, 3, 2, 7, 1, 8, 2, 3}
func main() {
fmt.Printf("input: %v\n", numbers)
stream := koazee.StreamOf(numbers)
fmt.Print("stream.Reduce(sum): ")
fmt.Println(stream.Reduce(func(acc, val int) int {
return acc + val
}).Int())
}
/**
go run main.go
input: [1 5 4 3 2 7 1 8 2 3]
stream.Reduce(sum): 36
*/This operation iterates over the element in the stream.
You can now optionally return an error as the second parameter to stop processing of the stream. The error will be available in stream.Out().Err().UserError().
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
)
type message struct {
user string
message string
}
var messages = []*message{
{user: "John", message: "Hello Jane"},
{user: "Jane", message: "Hey John, how are you?"},
{user: "John", message: "I'm fine! and you?"},
{user: "Jane", message: "Me too"},
}
func main() {
stream := koazee.StreamOf(messages)
stream.ForEach(func(m *message) {
fmt.Printf("%s: \"%s\"\n", m.user, m.message)
}).Do()
}
/**
go run main.go
John: "Hello Jane"
Jane: "Hey John, how are you?"
John: "I'm fine! and you?"
Jane: "Me too"
*/The main goal of Koazee is providing a set of operations that can be combined and being evaluated lazily.
package main
import (
"fmt"
"github.com/wesovilabs/koazee"
"strings"
)
type Person struct {
Name string
Male bool
Age int
}
var people = []*Person{
{"John Smith", true, 32},
{"Peter Pan", true, 17},
{"Jane Doe", false, 20},
{"Anna Wallace", false, 35},
{"Tim O'Brian", true, 13},
{"Celia Hills", false, 15},
}
func main() {
stream := koazee.
StreamOf(people).
Filter(func(person *Person) bool {
return !person.Male
}).
Sort(func(person, otherPerson *Person) int {
return strings.Compare(person.Name, otherPerson.Name)
}).
ForEach(func(person *Person) {
fmt.Printf("%s is %d years old\n", person.Name, person.Age)
})
fmt.Println("Operations are not evaluated until we perform stream.Do()\n")
stream.Do()
}
/**
go run main.go
Operations are not evaluated until we perform stream.Do()
Anna Wallace is 35 years old
Celia Hills is 15 years old
Jane Doe is 20 years old
*/| Operation | Description | Since |
|---|---|---|
| Add | It adds a new element in the last position | v0.0.1 |
| At | It returns the element in the given position | v0.0.1 |
| Contains | It checks if the given element is found in the stream. | v0.0.1 |
| Count | It returns the number of elements in a stream | v0.0.1 |
| DeleteAt | It remove the elements in the given position | v0.0.3 |
| Drop | It removes an element from the stream | v0.0.1 |
| DropWhile | It removes the elements in the stream that match with the given input function | v0.0.4 |
| Filter | It discards those elements that doesn't match with the provided filter | v0.0.1 |
| First | It returns the element in the first position | v0.0.1 |
| ForEach | It does something over all the elements in the stream. | v0.0.1 |
| GroupBy | It creates groups depending on the returned function value | v0.0.4 |
| IndexOf | It returns the first index of the element in the stream. | v0.0.3 |
| IndexesOf | It returns the index for all the occurrences of the element in the stream. | v0.0.4 |
| Last | It returns the element in the last position | v0.0.1 |
| LastIndexOf | It returns the last occurrence for the element in the stream. | v0.0.3 |
| Map | It converts the element in the stream | v0.0.1 |
| Pop | It extracts the first element in the stream and return this and the new stream | v0.0.3 |
| Reduce | It reduceshe stream to a single value by executing a provided function for each value of the stream | v0.0.1 |
| RemoveDuplicates | It removes duplicated elements. | v0.0.1 |
| Reverse | It reverses the sequence of elements in the stream. | v0.0.3 |
| Set | It replaces the element in the given index by the provided value | v0.0.3 |
| Sort | It sorts the elements in the stream | v0.0.1 |
| Take | It returns a stream with the elements between the given indexes | v0.0.3 |
A rich and growing set of examples can be found on koazee-samples
You can check the Benchmark for the Koazee operations here
A benchmark comparison with other frameworks can be found in Koazee vs Go-Funk vs Go-Linq
This is only the beginning! By the way, If you missed any operation in Koazee v0.0.3, or you found a bug, please create a new issue on Github or vote the existing ones!