?module example.com/hello
??
?go 1.20
??
?replace example.com/greetings => ../greetings
??
?require example.com/greetings v0.0.0-00010101000000-000000000000

?? go version
?go version go1.20.7 darwin/amd64

?? go help work
?Work provides access to operations on workspaces.
??
?Note that support for workspaces is built into many other commands, not
?just 'go work'.
??
?See 'go help modules' for information about Go's module system of which
?workspaces are a part.
??
?See https://go.dev/ref/mod#workspaces for an in-depth reference on
?workspaces.
??
?See https://go.dev/doc/tutorial/workspaces for an introductory
?tutorial on workspaces.
??
?A workspace is specified by a go.work file that specifies a set of
?module directories with the "use" directive. These modules are used as
?root modules by the go command for builds and related operations.  A
?workspace that does not specify modules to be used cannot be used to do
?builds from local modules.
??
?go.work files are line-oriented. Each line holds a single directive,
?made up of a keyword followed by arguments. For example:
??
?  go 1.18
??
?  use ../foo/bar
?  use ./baz
??
?  replace example.com/foo v1.2.3 => example.com/bar v1.4.5
??
?The leading keyword can be factored out of adjacent lines to create a block,
?like in Go imports.
??
?  use (
?    ../foo/bar
?    ./baz
?  )
??
?The use directive specifies a module to be included in the workspace's
?set of main modules. The argument to the use directive is the directory
?containing the module's go.mod file.
??
?The go directive specifies the version of Go the file was written at. It
?is possible there may be future changes in the semantics of workspaces
?that could be controlled by this version, but for now the version
?specified has no effect.
??
?The replace directive has the same syntax as the replace directive in a
?go.mod file and takes precedence over replaces in go.mod files.  It is
?primarily intended to override conflicting replaces in different workspace
?modules.
??
?To determine whether the go command is operating in workspace mode, use
?the "go env GOWORK" command. This will specify the workspace file being
?used.
??
?Usage:
??
?  go work <command> [arguments]
??
?The commands are:
??
?  edit ? ? ?  edit go.work from tools or scripts
?  init ? ? ?  initialize workspace file
?  sync ? ? ?  sync workspace build list to modules
?  use ? ? ? ? add modules to workspace file
??
?Use "go help work <command>" for more information about a command.

?? tree
?├── example
?└── mypkg

?? go mod init github.com/example
?go: /Users/oo7/Developer/works/example/go.mod already exists

?? go mod init github.com/mypkg
?go: /Users/oo7/Developer/works/mypkg/go.mod already exists

?package mypkg
??
?func Bar() {
?  println("this package is mypkg")
?}

?package main
??
?import (
?  "github.com/mypkg"
?)
??
?func main() {
?  mypkg.Bar()
?}

?? cd example/
?? go mod tidy
?go: finding module for package github.com/mypkg
?github.com/example imports
? ? ? ? ?github.com/mypkg: cannot find module providing package github.com/mypkg: invalid github.com import path "github.com/mypkg"
?? cd ../mypkg/
?? go mod tidy
?~/Developer/works/mypkg ? ? ?

?? cd example/
?? go run .
?main.go:4:2: no required module provides package github.com/mypkg; to add it:
? ? ? ? ?go get github.com/mypkg

?? go work init example mypkg
?go: /Users/oo7/Developer/works/go.work already exists

?go 1.20
??
?use (
?  ./example
?  ./mypkg
?)

?? go run .
?this package is mypkg

?? GOWORK=off go run main.go
?main.go:4:2: no required module provides package github.com/mypkg; to add it:
? ? ? ?  go get github.com/mypkg