go-stream

go-stream is a Go package to help processing stream of elements in more declarative manner.

Stream uses iterator pattern for visiting each element of a stream. It is lazy, which means the operations are not executed until terminal operation is called.

How to use

Install as follows:

go get github.com/rookiecj/go-stream

and uses as follows:

package main 

import (
	"fmt"

	s "github.com/rookiecj/go-stream/stream"
)

type myStruct struct {
	Name string
}

func main() {
	arr := []myStruct{
		{"a"},
		{"bbb"},

		{"c"},
		{"dddd"},
		{"e"},
		{"fffff"},
		{"g"},
		{"hhhhh"},
		{"i"},
	}

	s.FromSlice(arr).
	Filter(func(v myStruct) bool {
		return len(v.Name) == 1
	}).
	Map(func(v myStruct) myStruct {
		return myStruct{v.Name + "!"}
	}).
	ForEach(func(ele myStruct) {
		fmt.Println(ele)
	})
}

Operations

There 3 main operations:

• Builders
• Intermediates
• Terminals

Builders

Builder operations build a Stream from various sources like slice or array.

• FromSlice
• FromVar
• FromChan (Experimental)
• FromSource
• Indexed - for indexed Source

Intermediate operations

Intermediate operations generate new stream which consume data from upstream and apply operator on it.

• Filter
• Map/MapAny,MapIndex/MapIndexAny
• FlatMapConcat/FlatMapConcatAny(Experimental)
• FlatMapConcurrent
• Take, Skip
• Distinct, DistinctBy
• ZipWith/ZipWithAny
• ZipWithPrev (Experimental)
• Scan/ScanAny
• Window
• OnRecover (Experimental)
• WithIndex add an example for Indexed Source

Terminal operations

Terminal operations are collectors which trigger streams to work. and return the result of the stream.

• ForEach, ForEachIndex
• Collect/CollectTo
• Reduce/ReduceAny
• Fold/FoldAny
• Find/FindIndex/FindLast
• All,Any
• Count

Slightly more type safe functions are:

• ForEachAs, ForEachIndex
• CollectAs, CollectTo
• CollectAsSafe, CollectionToSafe
• ReduceAs
• FoldAs
• FindOrAs

TODO

• make ToStream lazy
• add more Builders
• Stream to interface
• add more intermediate operations
• add more safe terminal operations
• add doc
• add unittest
• remove Source/Collector from Stream
• make it more functional