Using options for data - vilinski/nemerle GitHub Wiki

Using options for data

Category: Lists, Tuples and Options
Description: Here we return an option from a function indicating the opening hours of a shop, if any.
Code:

using System;
using System.Console;
using Nemerle;

def openingHours(day)
{         // implicit match construction
  | DayOfWeek.Monday 
  | DayOfWeek.Tuesday 
  | DayOfWeek.Thursday 
  | DayOfWeek.Friday    => Some(9, 17)
  | DayOfWeek.Wednesday => Some(9, 19) // extended hours on Wednesday
  | _                   => None()
}
    
def today = DateTime.Now.DayOfWeek;

match (openingHours(today)) 
{
  | Some((s, f)) => WriteLine($"The shop's open today from $s:00-$f:00")
  | _            => WriteLine("The shop's not open today")
}

Execution Result (in case of Wednesday):

The shop's open today from 9:00-19:00

Execution Result (in case of Friday):

The shop's open today from 9:00-17:00

Execution Result (in other cases)

The shop's not open today