package main

import (
    "crypto/sha256"
    "fmt"
)

func main() {
    str := "some string to calculate hash"
    hash := sha256.New()

    hash.Write([]byte(str))
    sum := hash.Sum(nil) // the argument can be used to append to an existing byte slice

    fmt.Println(str)
    fmt.Printf("%x\n", sum)
}

// go run main.go 
// some string to calculate hash
// 7aad383b9ad516fa67057adc283ce2cf71858aff317a5e267adebfdbd5dda5fd