Basic Records - vilinski/nemerle GitHub Wiki

Basic Records

Category: Defining Types
Description: Records are concrete type definitions that hold data in an unordered, named structure.
Code:

using System;
using System.Console;
using Nemerle;

[Record]
class Point  
{ 
  public x : double; 
  public y : double;
  
  public override ToString() : string { $"{ x = $x, y = $y }" }
}

[Record]
class Triangle 
{ 
  public p1 : Point; 
  public p2 : Point; 
  public p3 : Point;
  
  public override ToString() : string { $"p1 = $p1, p2 = $p2, p3 = $p3" }
}

[Record]
class Vector 
{ 
  public dx : double; 
  public dy : double;
  
  public override ToString() : string { $"{ dx = $dx, dy = $dy }" }
}

def origin = Point(0.0, 0.0);
def onex   = Point(1.0, 0.0);
def oney   = Point(0.0, 1.0);

def diff(p1, p2) { Vector(p2.x - p1.x, p2.y - p1.y) }

def sides(tri) { (diff(tri.p2, tri.p1), diff(tri.p3, tri.p2), diff(tri.p1, tri.p3)) }
  
def triangle1 = Triangle(origin, onex, oney);
WriteLine($"triangle1 = $triangle1");
WriteLine($"sides(triangle1) = $(sides(triangle1))")

Execution Result:

triangle1 = p1 = { x = 0, y = 0 }, p2 = { x = 1, y = 0 }, p3 = { x = 0, y = 1 }
sides(triangle1) = ({ dx = -1, dy = 0 }, { dx = 1, dy = -1 }, { dx = 0, dy = 1 })