fix: decorator definition and example

Author: praisetompane

src/8_compound_statements/8.7._function_definitions/decorator.py

@@ -0,0 +1,63 @@
+"""
+  def decorators:
+      - formal: 𝑓: 𝑓 ↦ any 
+
+          - in words: a high order function to modify and execute functions/methods
+
+      - plain english: syntactic sugar for invoking a high order function directly and returning the parameter function's result.
+
+      - intuition: ???
+
+      - properties:
+        - specification: https://peps.python.org/pep-0318/
+
+      - examples:
+        - see function runtime tracker below: def timed
+
+      - use cases:
+        - aspect orientated programming:
+          - logging
+          
+      - proof: ???
+      
+  References: ???
+"""
+
+import time
+
+
+def timed(func):
+    def function_executor(*args, **kwargs):
+        print(f"Executing Function: {func.__name__} ")
+        start = time.time()
+        result = func(*args, **kwargs)
+        end = time.time()
+        print(
+            f"Function: {func.__name__} took {(end - start)*1000} miliseconds to complete."
+        )
+        return result
+
+    return function_executor
+
+
+@timed
+def square(numbers):
+    result = []
+    for num in numbers:
+        result.append(num * num)
+    return result
+
+
+@timed
+def square_map_implementation(numbers):
+    return list(map(lambda i: i * i, numbers))
+
+
+if __name__ == "__main__":
+    numbers = [i for i in range(10)]
+    print(square(numbers))
+    print(square_map_implementation(numbers))
+
+    # direct invocation
+    square_decorated = timed(square)
+    print(square_decorated(numbers))