added article about traits.js

articles/traitsjs/example.js

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+var Trait = require('traits').Trait;
+var print = require('sys').print;
+
+var TEquality = Trait({
+   equals: Trait.required,
+  differs: function(x) { return !this.equals(x); }
+});
+
+var TMagnitude = Trait.compose(TEquality, Trait({
+  smaller: Trait.required,
+  greater: function(x) { return !this.smaller(x) && this.differs(x) },
+  between: function(min, max) {
+    return min.smaller(this) && this.smaller(max);
+  }
+}));
+
+function TColor(rgb) {
+  return Trait.compose(TEquality, Trait({
+    get rgb() { return rgb; },
+    equals: function(col) { return col.rgb.equals(this.rgb); }
+  }));
+}
+
+function TCircle(center, radius, rgb) {
+  return Trait.compose(
+    TMagnitude,
+    TEquality,
+    Trait.resolve({ equals: 'equalColors' }, TColor(rgb)),
+    Trait({
+       center: center,
+       radius: radius,
+         area: function() { return Math.PI * this.radius * this.radius; },
+       equals: function(c) { return c.center === this.center &&
+                                    r.radius === this.radius },
+      smaller: function(c) { return this.radius < c.radius }
+  }));
+}
+
+function Circle(center, radius, rgb) {
+  return Trait.create(Object.prototype,
+                      TCircle(center, radius, rgb));
+}
+
+function test() {
+  var red = {
+    equals: function(o){ return ''+o === this.toString(); },
+    toString:function(){return 'red';}};
+  var c1 = Circle(0, 1, red);
+  var c2 = Circle(1, 2, red);
+  print('c1.area: ' + c1.area());
+  print('\nc1 < c2? ' + c1.smaller(c2));
+  print('\nc1 !== c2?' + c1.differs(c2));
+  print('\nc1 equalColors c2? '+c1.equalColors(c2));
+}

authors/Tom Van Cutsem.markdown

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+Github:   tvcutsem
+Email:    tomvc.be@gmail.com
+Homepage: http://soft.vub.ac.be/~tvcutsem
+Twitter: tvcutsem
+Location: Brussels, Belgium
+
+I'm a computer science researcher at the University of Brussels. My focus is on programming language technology. I serve on the ECMAScript technical committee and I'm the author of traits.js, a library for trait composition in Javascript, see http://traitsjs.org