nodemon --watch './*.go' --signal SIGTERM --exec 'go' run server.go 

---

Setup

Add GOPATH to your PATH

vim ~/.zshrc
export GOPATH=/Users/ayush/go
export PATH=$PATH:$GOPATH
export PATH=$PATH:$GOPATH/bin
source ~/.zshrc
sudo chmod 777 /bin/goimports

• Copy project from /usr/local/go/src to /Users/ayush/go/src/

Change VS Code Settings

"go.gopath": "/Users/ayush/go",
"go.toolsGopath": "/Users/ayush/go",

• Clone project in the User/ayush/go/src

Initialize our project as a Go module

go mod init github.com/aroraayush/golang-data-structures

Output

go: creating new go.mod: module github.com/aroraayush/golang-data-structures

• A new file will appear in your directory called go.mod
  • go.mod contains information about our module for others, such as the module name and Go version it is intended for

GOPATH vs GOROOT

Installing Golang via Homebrew automatically generates two directories critical to running Go:

• GOROOT ( /usr/local/go ):

  The Go "root" directory contains Go's source code. Homebrew will automatically register this path for you; there's little reason to mess around in here unless you're a Go contributor or if you're attempting to run multiple versions of Go.

• GOPATH ( /Users/ayush/go ):

  Unlike most programming languages, Go takes an opinionated stance that all projects and dependencies of the language should exist in a single directory known as the GOPATH . Any time we develop a Go project or install a third-party module, the actions taken ultimately happen inside this directory

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Go Packages

• Go programs are made up of "packages," which mirror packaging concepts in other programming languages (think modules in Python or packages in Java).

• Every Golang program contains a package called main, which serves as the project's entry point.

---

To make the package available to other apps, we need to install corresponding package in to go runtime

cd <package_name>
go install

• It will be stored in User/ayush/go/pkg/<os_type>/<project_name>

• For mac, os_type is darwin_amd64

  • <package_name>.a file is generated | Compiled package, linkable

• package is now avaible in main.go

---

Go Modules [third-party libraries]

Go modules are third-party libraries installed by Go. Modules are essentially projects which have been published for general use as dependencies in your projects.

---

Go Vendors

While modules can be installed to the /pkg/mod directory for global use, source projects can contain their own versions of these modules to avoid clashing dependency versions between projects (similar to Python virtual environments). While not required, you can choose to keep module versions project-specific (we will do this in our example).

Vendor directory

brew install dep
dep init # in src/main

• Gopkg.toml like pakage.json will be generated
• dep puts dependencies into the vendor folder

---

Go is a compiled language, we need to build our project before we can run it

go build
go run main.go

Code Formatting

go fmt

---

Do go run <filename> in each directory

---

nil reference

• golang uses nil instead of null or None

Primitives

• var

  var x string
  x = "Hello World"  // x is assigned the string "Hello World”
  

  OR

  var x string = "Hello World" 
  

• short declaration / walrus operator (:=)

  myvariable3 := 200
  

• const

  • Constants cannot be declared using the := syntax.
  • Constants can be character, string, boolean, or numeric values.

  const Pi = 3.14
  

• var vs short declaration operator (:=)

  • var - used to declare and initialize the variables inside and outside the functions. (global or local level scope)

  • :=   is used to declare and initialize the variables only inside the functions.

    • Declaration and initialization at the same time.

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Looping

Enhanced for loop

a := []string{"Foo", "Bar"} for idx, str := range a { fmt.Println(idx, str) }

0 Foo
1 Bar

• The range expression, a, is evaluated once before beginning the loop.
• The iteration values are assigned to the respective iteration variables, i and s, as in an assignment statement.
• The second iteration variable is optional.

Iterating each character of string

const s = "日本語" for i := 0; i < len(s); i++ { fmt.Printf("%x ", s[i]) }

e6 97 a5 e6 9c ac e8 aa 9e