Learning Functional Programming in Go

More reasons to design using interfaces

As if that's not enough reason to design using interfaces.

We also get access to a plethora of functionality. For example, when working with readers and writers, we get the following for free:

Free functionality	Description
io.Copy	// Copy copies from src to dst until either EOF is reached// on src or an error occurs. It returns the number of bytes// copied and the first error encountered while copying, if any.func Copy(dst Writer, src Reader) (written int64, err error) { return copyBuffer(dst, src, nil)}
io.LimitReader	// A LimitedReader reads from R but limits the amount of// data returned to just N bytes. Each call to Read// updates N to reflect the new amount remaining.// Read returns ...