Sync

Task/Constrained-genericity/D/constrained-genericity-1.d

@@ -1,6 +1,4 @@
-template IsEdible(T) {
-    enum IsEdible = is(typeof(T.eat()));
-}
+enum IsEdible(T) = is(typeof(T.eat));
 
 struct FoodBox(T) if (IsEdible!T) {
     T[] food;

Task/Constrained-genericity/Haskell/constrained-genericity-7.hs

@@ -0,0 +1,23 @@
+import Utils        # From the UniLib package to get the Class class.
+
+class Eatable:Class()
+end
+
+class Fish:Eatable(name)
+    method eat(); write("Eating "+name); end
+end
+
+class Rock:Class(name)
+    method eat(); write("Eating "+name); end
+end
+
+class FoodBox(A)
+initially
+    every item := !A do if "Eatable" == item.Type() then next else bad := "yes"
+    return /bad
+end
+
+procedure main()
+    if FoodBox([Fish("salmon")]) then write("Edible") else write("Inedible")
+    if FoodBox([Rock("granite")]) then write("Edible") else write("Inedible")
+end

Task/Constrained-genericity/Nemerle/constrained-genericity.nemerle

@@ -0,0 +1,46 @@
+using System.Collections.Generic;
+
+interface IEatable
+{
+    Eat() : void;
+}
+
+class FoodBox[T] : IEnumerable[T]
+  where T : IEatable
+{
+    private _foods : list[T] = [];
+
+    public this() {}
+
+    public this(items : IEnumerable[T])
+    {
+        this._foods = $[food | food in items];
+    }
+
+    public Add(food : T) : FoodBox[T]
+    {
+        FoodBox(food::_foods);
+    }
+
+    public GetEnumerator() : IEnumerator[T]
+    {
+        _foods.GetEnumerator();
+    }
+}
+
+class Apple : IEatable
+{
+    public this() {}
+
+    public Eat() : void
+    {
+        System.Console.WriteLine("nom..nom..nom");
+    }
+}
+
+mutable appleBox = FoodBox();
+repeat(3) {
+    appleBox = appleBox.Add(Apple());
+}
+
+foreach (apple in appleBox) apple.Eat();