From f972303c983c8bdc1d98396f53fae60cded76bd1 Mon Sep 17 00:00:00 2001
From: Aleksey Zubakov <aleks.zubakov@gmail.com>
Date: Tue, 27 Sep 2022 02:21:28 +0300
Subject: [PATCH] Code from second seminar.

Here are examples of *functions* and *higher-order functions*.
All signatures of functions are annotated with types and could
be typechecked with mypy or pyright.
---
 02/01.py      |  3 +++
 02/02.py      |  5 +++++
 02/03.py      | 37 +++++++++++++++++++++++++++++++++++++
 02/04.py      | 19 +++++++++++++++++++
 02/README.md  | 31 +++++++++++++++++++++++++++++++
 02/main_01.py | 19 +++++++++++++++++++
 6 files changed, 114 insertions(+)
 create mode 100644 02/01.py
 create mode 100644 02/02.py
 create mode 100644 02/03.py
 create mode 100644 02/04.py
 create mode 100644 02/README.md
 create mode 100644 02/main_01.py

diff --git a/02/01.py b/02/01.py
new file mode 100644
index 0000000..67bddb6
--- /dev/null
+++ b/02/01.py
@@ -0,0 +1,3 @@
+from main_01 import is_prime
+
+print(is_prime(17))
diff --git a/02/02.py b/02/02.py
new file mode 100644
index 0000000..63f52ae
--- /dev/null
+++ b/02/02.py
@@ -0,0 +1,5 @@
+def square(x: int) -> int:
+    pass
+
+
+square("asdasd")
diff --git a/02/03.py b/02/03.py
new file mode 100644
index 0000000..29aaba0
--- /dev/null
+++ b/02/03.py
@@ -0,0 +1,37 @@
+import doctest
+
+from typing import Callable
+
+
+# term :: int -> int
+def cube(x: int) -> int:
+    """
+    Evaluates cube of given number.
+    >>> cube(3)
+    27
+    >>> cube(5)
+    125
+    """
+    return x * x * x
+
+
+# term :: int -> int
+def summation(
+    n: int,
+    term: Callable[[int], int],
+) -> int:
+    """
+    Sums first n numbers of series.
+    >>> summation(5, cube)
+    225
+    >>> summation(5, lambda k: 8 // ((4 * k - 3) * (4 * k - 1)))
+    2
+    """
+    total = 0
+    for k in range(1, n + 1):
+        total += term(k)
+    return total
+
+
+if __name__ == "__main__":
+    doctest.testmod()
diff --git a/02/04.py b/02/04.py
new file mode 100644
index 0000000..5652d63
--- /dev/null
+++ b/02/04.py
@@ -0,0 +1,19 @@
+from typing import Callable, Tuple
+
+type_F = Callable[[int], int]
+
+
+def factory(total: int) -> Tuple[type_F, type_F]:
+    def adder(k):
+        return k + total
+
+    def subtractor(k):
+        return total - k
+
+    return adder, subtractor
+
+
+if __name__ == "__main__":
+    add, min = factory(5)
+    print(add(1))
+    print(min(3))
diff --git a/02/README.md b/02/README.md
new file mode 100644
index 0000000..4a59265
--- /dev/null
+++ b/02/README.md
@@ -0,0 +1,31 @@
+### Что здесь лежит?
+- `01.py` и `main_01.py` демонстрируют как разбивать
+код на отдельный файлы;
+- `02.py` -- пример простой типизированной функции;
+- `03.py`-- обобщение частичной суммы ряда с помощью функций;
+- `04.py` -- примеры функций-замыканий;
+
+### Как запускать?
+
+Желательно установить [mypy](https://github.com/python/mypy) или даже
+[pyright](https://github.com/microsoft/pyright) и проверять типизацию
+ими перед запусками:
+```sh
+$ mypy *.py
+```
+или
+```sh
+$ mypy 01.py
+```
+
+`01.py` и `02.py` можно запустить, как  и в прошлый раз:
+```sh
+$ python 01.py
+```
+
+Если файл содержит doctest _(прим.: пример в комментарии к функции; да, он
+рабочий)_, добавьте флаг `-v` в конце:
+
+```sh
+$ python 03.py -v
+```
diff --git a/02/main_01.py b/02/main_01.py
new file mode 100644
index 0000000..7e97720
--- /dev/null
+++ b/02/main_01.py
@@ -0,0 +1,19 @@
+def is_prime(n: int) -> bool:
+    """
+    >>> is_prime(10)
+    True
+    >>> is_prime(17)
+    True
+    >>> is_prime(21)
+    False
+    """
+    for el in range(2, n):
+        if n % el == 0:
+            return False
+    return True
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()