Proper way to import a package - go

Question

Being new to Go this is the way I'm currently importing a package that I created. As an example:
folder path: loader\types
filename: types.go
package types
func SomeVal() string {
return "ABC"
}
folder path: loader
filename: main.go
package main
import (
"loader/types
)
func main() {
fmt.PrintLn(SomeVal())
}
My question is I create another application name tester and want to reuse the types.go code, I would have to do the following
folder path: tester\types
filename: types.go
package types
func SomeVal() string {
return "ABC"
}
folder path: tester
filename: main.go
package main
import (
"tester/types"
)
func main() {
fmt.PrintLn(SomeVal())
}
Is there a way to avoid calling the root folder "tester" or "loader" in the import from the main.go files? The issue I'm facing is that I have another package
folder path: loader\view
filename: view.go
package view
import (
"loader/types"
)
func AnotherValue() string {
return SomeVal()
}
So if I decide to use both loader/types and loader/view in another project, I would have to change the root folder when importing.
Again I'm new to Go so I could be looking at it incorrectly.
Thanks

Answer 1

If you want to use your modules (loader) which contains types and view packages in other project (e.g. in other repositories), you would need to transform loader into a reusable module/library. Go makes use of Git for this.
This involves creating a go.mod file to indicate that this project is a valid Go module. As you said, https://go.dev/doc/tutorial/create-module is a good starting point.
Usually, you can put this module in your repository, or in github, and so the module name should be the Git repo path, e.g. gihub.com/adviner/loader, something that you would put on top of your go.mod file.
go.mod in loader project:
module github.com/adviner/loader
go 1.19
If this module is hosted in public repo like github, Go will be able to retrieve it later. If you host it in a private repository that requires authentication to download, read more about using the GOPRIVATE environment variable from https://go.dev/ref/mod#environment-variables. Another approach is to just store this module in your local directory and use replace when using this module from another project.
It is a best practice that a Go project always have a go.mod file. So when you create a new project, let's say projecta, you might have a go.mod like this:
module github.com/adviner/projecta
go 1.19
require (
github.com/adviner/loader v1.0.0
)
replace (
github.com/adviner/loader => ../path/to/loader
)
We can use replace to replace the module with a local path so Go does not try to look for the module in github.com. This is not meant to be a permanent solution though. Usually you can just put your library in github or other private repository and remove the replace statement so you can work on the same project without having to transfer the loader module from one device to another.
PS. v1.0.0 here is the version that is tagged in your loader module. It is usually a tag that is added in your Git commit. If you don't have any Git tag in the commit you can use the commit ID.
PS. When naming your module github.com/adviner/loader, importing packages inside loader should now be done like so (even in the loader project itself): import github.com/adviner/loader/view and no longer loader/view.
Reference to go.mod and Go module system can be found here: https://go.dev/ref/mod