I/O readers and writers

Canonical guidance

• accept io.Reader or io.Writer when data should stream
• keep ownership of closing resources explicit
• use standard adapters before inventing custom interfaces

Use when

• large payloads
• network or file streaming
• pipeline-style transformations

Avoid

• forcing everything through []byte
• closing readers you did not open unless the contract says so
• custom copy loops without a reason

Preferred pattern

func CopyJSON(dst io.Writer, src io.Reader) error {
	_, err := io.Copy(dst, src)
	return err
}

Anti-pattern

• reading entire streams into memory when incremental processing would do

Explanation: This anti-pattern is tempting because byte slices are easy to inspect, but it turns streaming problems into memory problems.

Why

• Reader and Writer interfaces are Go’s standard streaming composition points