IT notes

To check that x implements y, example:

package main

import (
    "fmt"
    "io"
    "os"
)

var _ io.ReadCloser = (*os.File)(nil)

func main() {
    fmt.Println("Hello, playground")
}

https://play.golang.org/p/hoi5_GQEpD

To check that os.File is an io.ReadCloser:

var _ io.ReadCloser = (*os.File)(nil)

package main

import (
	"fmt"
	"io"
	"os"
)

var _ io.ReadCloser = (*os.Process)(nil)

func main() {
	fmt.Println("Hello, playground")
}

https://play.golang.org/p/7uHmjn3ggT

The error in this case would be:

main.go:9: cannot use (*os.Process)(nil) (type *os.Process) as type io.ReadCloser in assignment:
*os.Process does not implement io.ReadCloser (missing Close method)