pray is a tool for finding unused public variables, constants, types, functions and methods. Given a package, it will explore all public items in that package and check for the usage of these items in a set of specified packages. Here is a sample usage:

% pray -src github.com/tsuru/config github.com/tsuru/tsuru/app
/Users/f/src/github.com/tsuru/config/checker.go:10:6: Check is unused
/Users/f/src/github.com/tsuru/config/config.go:113:6: WriteConfigFile is unused
/Users/f/src/github.com/tsuru/config/config.go:229:6: GetUint is unused
/Users/f/src/github.com/tsuru/config/config.go:75:6: ReadAndWatchConfigFile is unused
/Users/f/src/github.com/tsuru/config/config.go:296:6: GetList is unused
/Users/f/src/github.com/tsuru/config/config.go:208:6: GetFloat is unused

The flag -src specifies the source packages, and then users can provide the set of packages for searching. Users can also use the Go notation for expanding subpackages:

% pray -src github.com/tsuru/config github.com/tsuru/tsuru/...

Currently, it works, but may eat your entire system memory. It also gives false negatives when analyzing public methods of a type that implement an interface, and the method is called only through the interface, so it still reports that MyError.Error is unused in the code below:

type MyError struct {
	message string
}

func (err *MyError) Error() string {
	return err.message
}

func getError() string {
	var err error = &MyError{}
	return err.Error()
}

Feel free to send any pull requests or open issues. Please ensure that your code follow gofmt and goimports rules.