Proposal to add ReaderFunc to package io

ReaderFunc.go

/*
https://play.golang.org/p/iWDGHj_-X_

This programs generates 32 random bytes formatted à la "hexdump -C".

It does it in just 2 lines of code using the power of the standard library
and a trick to convert a func Read([]byte) (int, error) into an io.Reader.

Inspiration: see HandlerFunc in net/http

Note: on the Go Playground the seed is NOT random.

Author: Olivier Mengué
https://github.com/dolmen-go/

*/
package main

import (
	"encoding/hex"
	"io"
	"math/rand" // alternative: "crypto/rand"
	"os"
)

// ReaderFunc allows to convert an io.Reader.Read-like function into an io.Reader
type ReaderFunc func([]byte) (n int, err error)

// Read implements the io.Reader interface
func (read ReaderFunc) Read(p []byte) (int, error) {
	return read(p)
}

func main() {

	// Transform func rand.Read into an io.Reader
	randReader := ReaderFunc(rand.Read)

	// Read 32 bytes from randReader and dump in hex
	io.CopyN(hex.Dumper(os.Stdout), randReader, 32)
}