Simple way to get user (standard user keyboard input)

[mahSource]

At a minimum, there should be something similar in grain, akin to this six line C++ program, to get user input. There should be documentation for this write up front in the Guide with a simple hello "name" program that lets the user input their name and it provides a greeting back.

#include <iostream>
int main() {
  std::cout << "\nEnter an integer: ";
  int num{};
  std::cin >> num;
  std::cout << num << " doubled is: " << num * 2 << '\n';
}

Output

Enter an integer: 25
25 doubled is: 50

[ospencer]

This is possible—it's reading from the stdin file descriptor: i.e. doing https://grain-lang.org/docs/stdlib/sys/file#File-fdRead on https://grain-lang.org/docs/stdlib/sys/file#File-stdin.

You can track the work being done to make it nicer via this issue: #211