1. Install Atom. You can get atom from here
2. Go to Atom settings (ctrl+,). Packages -> Install go-plus package (go-plus)

After Installing go-plus in Atom:

3. Get these dependencies using go get or another dependency manager: (open a console and run these commands)

go get -u golang.org/x/tools/cmd/goimports

go get -u golang.org/x/tools/cmd/gorename

go get -u github.com/sqs/goreturns

go get -u github.com/nsf/gocode

go get -u github.com/alecthomas/gometalinter

go get -u github.com/zmb3/gogetdoc

go get -u github.com/rogpeppe/godef

go get -u golang.org/x/tools/cmd/guru

4. Install Gulp (Gulpjs) using npm or any other package manager (gulp-getting-started-doc):

$ npm install --global gulp

var gulp = require('gulp');
var path = require('path');
var shell = require('gulp-shell');

var goPath = 'src/mypackage/**/*.go';


gulp.task('compilepkg', function() {
  return gulp.src(goPath, {read: false})
    .pipe(shell(['go install <%= stripPath(file.path) %>'],
      {
          templateData: {
            stripPath: function(filePath) {
              var subPath = filePath.substring(process.cwd().length + 5);
              var pkg = subPath.substring(0, subPath.lastIndexOf(path.sep));
              return pkg;
            }
          }
      })
    );
});

gulp.task('watch', function() {
  gulp.watch(goPath, ['compilepkg']);
});

In the code above we defined a compliepkg task that will be triggered every time any go file in goPath (src/mypackage/) or subdirectories changes. the task will run the shell command go install changed_file.go

After creating the gulp file in go path and define the task open a command line and run:

gulp watch

You'll se something like this everytime any file changes:

package mypackage

var PublicVar string = "Hello, dear reader!"

//Calculates the factorial of given number recursively!
func Factorial(x uint) uint {
    if x == 0 {
        return 1
    }
    return x * Factorial(x-1)
}

Now you can start writing your own go code with auto-completion using Atom and Gulp:

package main

import (
    "fmt"
    "mypackage"
)

func main() {

    println("4! = ", mypackage.Factorial(4))

}