Records with Members - vilinski/nemerle GitHub Wiki

Records with Members

Category: Defining Types
Description: Nemerle allows values to be associated with type names, i.e. the type name can be used as a container for 'members' of that type. These are treated the same way as .NET object model members.
Code:

using System;
using System.Console;
using Nemerle;

[Record]
class PointWithMembers
{
  public x: double; 
  public y: double;
  
  public static Origin : PointWithMembers { get { PointWithMembers(0.0, 0.0) } }

  public static @+(p : PointWithMembers, v : VectorWithMembers) : PointWithMembers
  {
    PointWithMembers(p.x + v.dx, p.y + v.dy)
  }

  public override ToString() : string { $"{ x = $x, y = $y }" }
}

[Record]
class VectorWithMembers
{
  public dx : double; 
  public dy : double;

  public static Zero : VectorWithMembers { get { VectorWithMembers(0.0, 0.0) } }
  public static OneX : VectorWithMembers { get { VectorWithMembers(1.0, 0.0) } }
  public static OneY : VectorWithMembers { get { VectorWithMembers(0.0, 1.0) } }

  public static @+(v1 : VectorWithMembers, v2 : VectorWithMembers) : VectorWithMembers
  { 
    VectorWithMembers(dx = v1.dx + v2.dx, dy = v1.dy + v2.dy)
  }
  
  public override ToString() : string { $"{ dx = $dx, dy = $dy }" }
}

module Test
{
  
  Main() : void
  {
    WriteLine($"Point.Origin = $(PointWithMembers.Origin)");
    WriteLine($"Point.Origin + Vector.OneX = $(PointWithMembers.Origin + VectorWithMembers.OneX)");
    WriteLine($"Vector.OneX + Vector.OneY = $(VectorWithMembers.OneX + VectorWithMembers.OneY)");
  }
  
}

Execution Result:

Point.Origin = { x = 0, y = 0 }
Point.Origin + Vector.OneX = { x = 1, y = 0 }
Vector.OneX + Vector.OneY = { dx = 1, dy = 1 }