Variables

Go is statically typed — every variable has a fixed type, checked at compile time, not at runtime. Coming from Python, this is the biggest day-to-day difference you'll feel, so let's get comfortable with it immediately.

Declaring variables

The explicit form:

var age int = 34
var name string = "Haleh"

You'll rarely write it that way inside a function, though. Go infers the type from the value, so this is equivalent and far more common:

age := 34
name := "Haleh"

:= declares and initializes in one step. It only works for a brand-new variable inside a function — you can't use it to declare package-level variables, and you can't use it to reassign an existing one (use plain = for that).

age := 34
age = 35   // reassignment, no :=

Try mixing types where Go doesn't expect them:

age := 34
age = "thirty-five"

./main.go:6:7: cannot use "thirty-five" (untyped string constant) as int value in assignment

That's the compiler catching a bug that, in Python, wouldn't surface until the line actually ran — possibly in production, possibly much later than the line that caused it.

Naming and exporting

Go doesn't have public/private keywords. Instead, capitalization controls visibility:

var ExportedName = "visible outside this package"
var unexportedName = "only visible inside this package"

An identifier starting with an uppercase letter is exported (importable by other packages); lowercase means package-private. You'll see this rule everywhere once you know it's there — it's why standard library functions like fmt.Println and strings.Split are capitalized. This rule isn't just for variables — it applies the same way to functions, types, and constants, which you'll meet next.