September 2017 Update

Task/Polymorphism/Jq/polymorphism-1.jq

@@ -0,0 +1,14 @@
+def Point(x;y): {"type": "Point", "x": x, "y": y};
+def Point(x): Point(x;0);
+def Point: Point(0);
+
+def Circle(x;y;r): {"type": "Circle", "x": x, "y": y, "r": r};
+def Circle(x;y): Circle(x;y;0);
+def Circle(x): Circle(x;0);
+def Circle: Circle(0);
+
+def print:
+  if  .type == "Circle" then "\(.type)(\(.x); \(.y); \(.r))"
+  elif .type == "Point" then "\(.type)(\(.x); \(.y))"
+  else empty
+  end;

Task/Polymorphism/Jq/polymorphism-2.jq

@@ -0,0 +1,5 @@
+# keyname should be (or evaluate to) a string
+def set(keyname; value):
+  if type == "object" and .type and has(keyname) then .[keyname] = value
+  else error("set: invalid type: \(.)")
+  end;

Task/Polymorphism/Jq/polymorphism-3.jq

@@ -0,0 +1 @@
+Circle(0;1;2) | .x = 1 | print