From 9b559ea706047301b0a9263935cad3a23f62452d Mon Sep 17 00:00:00 2001
From: Kilian Lieret <kilian.lieret@posteo.de>
Date: Wed, 2 Nov 2022 15:55:53 -0400
Subject: [PATCH] Add mypy examples

---
 examples/typed_python/example_1.py        |  3 +++
 examples/typed_python/example_2.py        | 12 ++++++++++++
 examples/typed_python/example_protocol.py | 17 +++++++++++++++++
 examples/typed_python/readme.md           | 11 +++++++++++
 slides.md                                 | 15 ++++++++++-----
 5 files changed, 53 insertions(+), 5 deletions(-)
 create mode 100644 examples/typed_python/example_1.py
 create mode 100644 examples/typed_python/example_2.py
 create mode 100644 examples/typed_python/example_protocol.py
 create mode 100644 examples/typed_python/readme.md

diff --git a/examples/typed_python/example_1.py b/examples/typed_python/example_1.py
new file mode 100644
index 0000000..e7f191c
--- /dev/null
+++ b/examples/typed_python/example_1.py
@@ -0,0 +1,3 @@
+def f(x: float) -> float:
+    y = x**2
+    return y
diff --git a/examples/typed_python/example_2.py b/examples/typed_python/example_2.py
new file mode 100644
index 0000000..3c9b70c
--- /dev/null
+++ b/examples/typed_python/example_2.py
@@ -0,0 +1,12 @@
+from __future__ import annotations
+
+
+def f(x: int) -> list[int]:
+    return list(range(x))
+
+
+def g(x: str | int) -> str:
+    if isinstance(x, str):
+        return x.lower()
+    else:
+        return x
diff --git a/examples/typed_python/example_protocol.py b/examples/typed_python/example_protocol.py
new file mode 100644
index 0000000..847ddd8
--- /dev/null
+++ b/examples/typed_python/example_protocol.py
@@ -0,0 +1,17 @@
+import typing
+from typing import Protocol  # or typing_extensions for < 3.8
+
+class Duck(Protocol):
+    def quack(self) -> str:
+        ...
+
+def pester_duck(a_duck: Duck) -> None:
+    print(a_duck.quack())
+
+class MyDuck:
+    def quack(self) -> str:
+        return "quack"
+
+# Check explicitly that MyDuck is implementing the Duck protocol
+if typing.TYPE_CHECKING:
+    _: Duck = typing.cast(MyDuck, None)
diff --git a/examples/typed_python/readme.md b/examples/typed_python/readme.md
new file mode 100644
index 0000000..1a15b87
--- /dev/null
+++ b/examples/typed_python/readme.md
@@ -0,0 +1,11 @@
+# Typed python
+
+Install `mypy`:
+
+```bash
+pipx install mypy
+```
+
+Run `mypy example_1.py`, etc.
+
+Some of the files have mistakes in them, can you fix them?
diff --git a/slides.md b/slides.md
index a04c8ac..e68d884 100644
--- a/slides.md
+++ b/slides.md
@@ -677,8 +677,6 @@ To run: `pip install pytest` and then `pytest` to discover & run them all.
 
 ## First tip: your `project.toml` file
 
-Reminder: https://scikit-hep.org/developer/pytest is a great place to look for tips!
-
 ```toml
 [tool.pytest.ini_options]
 minversion = "6.0"  # minimal version of pytest
@@ -702,6 +700,10 @@ testpaths = ["tests"]  # search for tests in "test" directory
 * You can also add `breakpoint()` in your code to get into a debugger
 
 
+&nbsp;
+
+Reminder: https://scikit-hep.org/developer/pytest is a great place to look for tips!
+
 ---
 layout: two-cols
 ---
@@ -784,8 +786,6 @@ System IO, GUIs, hardware, slow processes; there are a lot of things that are ha
 
 * **💡Solution:** Add types and run a type checker.
 
-Typed code looks like this:
-
 ```python
 def f(x: float) -> float:
     y = x**2
@@ -795,7 +795,10 @@ def f(x: float) -> float:
 * Functions always have types in and out
 * Variable definitions rarely have types
 
-How do we use it?
+</v-click>
+<v-click>
+
+How do we use it? (requires `pipx install mypy`)
 
 ```bash
 mypy --strict tmp.py
@@ -804,6 +807,8 @@ mypy --strict tmp.py
 
 Some type checkers: MyPy (Python), Pyright (Microsoft), Pytype (Google), or Pyre (Meta).
 
+👉 Example files available [here](https://github.com/klieret/everything-you-didnt-now-you-needed/tree/main/examples/typed_python).
+
 </v-click>
 
 ---