Just another update

Task/Abstract-type/Mathematica/abstract-type.math

@@ -0,0 +1,26 @@
+(* Define an interface, Foo, which requires that the functions Foo, Bar, and Baz be defined *)
+InterfaceFooQ[obj_] := ValueQ[Foo[obj]] && ValueQ[Bar[obj]] && ValueQ[Baz[obj]];
+PrintFoo[obj_] := Print["Object ", obj, " does not implement interface Foo."];
+PrintFoo[obj_?InterfaceFooQ] := Print[
+   "Foo: ", Foo[obj], "\n",
+   "Bar: ", Bar[obj], "\n",
+   "Baz: ", Baz[obj], "\n"];
+
+(* Extend all integers with Interface Foo *)
+Foo[x_Integer] := Mod[x, 2];
+Bar[x_Integer] := Mod[x, 3];
+Baz[x_Integer] := Mod[x, 5];
+
+(* Extend a particular string with Interface Foo *)
+Foo["Qux"] = "foo";
+Bar["Qux"] = "bar";
+Baz["Qux"] = "baz";
+
+(* Print a non-interface object *)
+PrintFoo[{"Some", "List"}];
+(* And for an integer *)
+PrintFoo[8];
+(* And for the specific string *)
+PrintFoo["Qux"];
+(* And finally a non-specific string *)
+PrintFoo["foobarbaz"]

Task/Abstract-type/Oberon-2/abstract-type.oberon-2

@@ -0,0 +1,7 @@
+TYPE
+  Animal = POINTER TO AnimalDesc;
+  AnimalDec = RECORD [ABSTRACT] END;
+
+  (* Cat inherits from Animal *)
+  Cat = POINTER TO CatDesc;
+  CatDesc = RECORD (AnimalDesc) END;

Task/Abstract-type/Seed7/abstract-type.seed7

@@ -0,0 +1,5 @@
+const type: myInterf is sub object interface;
+
+const func integer: method1 (in myInterf: interf, in float: aFloat) is DYNAMIC;
+const func integer: method2 (in myInterf: interf, in string: name) is DYNAMIC;
+const func integer: add (in myInterf: interf, in integer: a, in integer: b) is DYNAMIC;

Task/Abstract-type/Standard-ML/abstract-type-1.ml

@@ -0,0 +1,6 @@
+signature QUEUE = sig
+  type 'a queue
+  val empty : 'a queue
+  val enqueue : 'a -> 'a queue -> 'a queue
+  val dequeue : 'a queue -> ('a * 'a queue) option
+end

Task/Abstract-type/Standard-ML/abstract-type-2.ml

@@ -0,0 +1,6 @@
+signature LIST_QUEUE = sig
+  type 'a queue = 'a list
+  val empty : 'a queue
+  val enqueue : 'a -> 'a queue -> 'a queue
+  val dequeue : 'a queue -> ('a * 'a queue) option
+end