internal static void Hypothenuse()
{
string s1 = Prompt("First leg:")
, s2 = Prompt("Second leg:");
var result = from a in Double.Parse(s1)
let aa = a * a
from b in Double.Parse(s2)
let bb = b * b
select Math.Sqrt(aa + bb);
WriteLine(result.Match(
() => "Please enter two valid, positive numbers",
(h) => $"The hypothenuse is {h}"));
}
internal static void _main()
{
WriteLine("Enter a number, for which this program will calculate the square root:");
var input = ReadLine();
var result = from d in Double.Parse(input)
where 0 <= d
select Math.Sqrt(d);
WriteLine(result.Match(
Some: r => $"sqrt({input}) = {r}",
None: () => "Please enter a valid, positive number"));
ReadKey();
}
static Validation <double> Validate(string s)
=> Double.Parse(s).Match(
() => Error($"'{s}' is not a valid number"),
d => Valid(d));