Importing Packages
import "package/path"
import (
"package/one"
alias "package/two"
_ "package/three"
)Basic Import Syntax
The import keyword, followed by a package's import path in quotes, makes that package's exported identifiers available, accessed with a dot after the package's name (usually the last element of its path).
Example: Basic Import Syntax
// Every Go file belongs to a package; main builds an executable
package main
// Import the fmt package
import "fmt"
// main is where the program starts running
func main() {
// Print the values followed by a newline
fmt.Println("fmt package imported and used")
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Grouped Imports
When importing several packages, Go convention groups them in one parenthesized block rather than repeating the import keyword on each line, which gofmt keeps neatly sorted.
Example: Grouped Imports
// Every Go file belongs to a package; main builds an executable
package main
// Import the packages this program uses
import (
"fmt"
"strings"
)
// main is where the program starts running
func main() {
// Print the values followed by a newline
fmt.Println(strings.ToUpper("go imports"))
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Aliasing an Import
An import can be given a different local name by placing an identifier before its path, useful when two imported packages would otherwise share the same default name.
Example: Aliasing an Import
// Every Go file belongs to a package; main builds an executable
package main
// Import the packages this program uses
import (
"fmt"
str "strings"
)
// main is where the program starts running
func main() {
// Print the values followed by a newline
fmt.Println(str.ToLower("ALIASED IMPORT"))
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Blank Imports for Side Effects
Prefixing an import path with _ imports it purely for its side effects (like an init() function registering something), without making its identifiers usable or triggering an 'unused import' error.
Example: Blank Imports for Side Effects
package main
import (
"fmt"
_ "strings" // blank import: runs init side effects only, not actually needed here
)
func main() {
fmt.Println("blank imports run side effects without exposing identifiers")
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- Leaving an unused import in a file, which is a compile-time error in Go, not just a lint warning.
- Forgetting to prefix imported identifiers with the package name, e.g. calling Println() instead of fmt.Println().
- Importing a package purely for its side effects without using the blank identifier (_) prefix, causing an 'imported and not used' error.
- import "path" brings a package into scope, accessed via its package name as a prefix.
- Multiple imports are grouped in a single parenthesized import block by convention.
- An unused import is a compile-time error, keeping import lists always accurate.
- A blank import, _ "path", runs a package's init() side effects without exposing its identifiers.
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