Data update

Task/Parametric-polymorphism/Python/parametric-polymorphism-2.py

@@ -0,0 +1,33 @@
+"""Parametric polymorphism. Requires Python >= 3.12."""
+
+from typing import Callable
+from typing import Iterable
+
+
+class Tree[T]:
+    def __init__(self, value: T):
+        self.value = value
+        self.left: Tree[T] | None = None
+        self.right: Tree[T] | None = None
+
+    def map(self, func: Callable[[T], T]) -> Iterable[T]:
+        yield func(self.value)
+        if self.left is not None:
+            yield from self.left.map(func)
+        if self.right is not None:
+            yield from self.right.map(func)
+
+
+if __name__ == "__main__":
+    tree = Tree(7)
+    tree.left = Tree(42)
+    tree.right = Tree(101)
+    tree.right.left = Tree(1)
+
+    # Fails static type checking as "foo" is not an int.
+    # tree.left.left = Tree[int]("foo")
+
+    # Fails static type checking as Tree[str] is not Tree[int]
+    # tree.left.left = Tree("bar")
+
+    print(list(tree.map(lambda v: v + 1)))  # [8, 43, 102, 2]