type Command struct {
	Path string   
	Env  []string
	Cmd  string 
	Args []string
}

type Rename struct {
	Path   string 
	Regexp string 
	Target string 
}

//...

type Ruler interface {
	Command | Replace | Remove | Rename | Copy | Make
}

type Action struct {
        Type      Type  //Enumeration values bound to Ruler types
	Commands []Command 
	Replaces []Replace 
	Removes  []Remove 
	Renames  []Rename 
	Copies   []Copy   
	Makes    []Make   
}


func getRulers[R Ruler](action Action) []R {
	switch action.Type {
	case TypeCommand:
		return action.Commands
	case TypeReplace:
		return action.Replaces
	case TypeRemove:
		return action.Removes
	case TypeRename:
		return action.Renames
	case TypeCopy:
		return action.Copies
	case TypeMake:
		return action.Makes
	}
	return nil
}

.\action.go:48:10: cannot use action.Commands (variable of type []Command) as type []R in return statement

func castRuleCommand[R Ruler](r []Command) []R {
	return *(*[]R)(unsafe.Pointer(&r))
}