From eea8f8383d7b1862ab3d085ea98bd430dd00800a Mon Sep 17 00:00:00 2001
From: Marco Gorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Fri, 23 Feb 2024 10:09:15 +0000
Subject: [PATCH] mypy in pre-commit

---
 .pre-commit-config.yaml   | 7 ++++++-
 narwhals/spec/__init__.py | 3 +++
 tpch/q1.py                | 2 +-
 tpch/q4.py                | 2 +-
 tpch/q5.py                | 2 +-
 5 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index be4682e75..4c7ca1436 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -8,4 +8,9 @@ repos:
       args: [--fix]
     # Run the formatter.
     - id: ruff-format
-  
\ No newline at end of file
+-   repo: https://github.com/pre-commit/mirrors-mypy
+    rev: 'v1.8.0'
+    hooks:
+    -   id: mypy
+        additional_dependencies: ['polars==0.20.10', 'pytest==8.0.1']
+        exclude: utils
diff --git a/narwhals/spec/__init__.py b/narwhals/spec/__init__.py
index 89502e37a..972753c8c 100644
--- a/narwhals/spec/__init__.py
+++ b/narwhals/spec/__init__.py
@@ -18,6 +18,9 @@ def alias(self, name: str) -> Self:
     def cast(self, dtype: DType) -> Self:
         ...
 
+    def __eq__(self, other: object) -> Expr:  # type: ignore[override]
+        ...
+
     def __and__(self, other: Any) -> Expr:
         ...
 
diff --git a/tpch/q1.py b/tpch/q1.py
index 34dd15249..82ff14d41 100644
--- a/tpch/q1.py
+++ b/tpch/q1.py
@@ -8,7 +8,7 @@
 polars.Config.set_tbl_cols(10)
 
 
-def q1(df_raw: Any) -> None:
+def q1(df_raw: Any) -> Any:
     var_1 = datetime(1998, 9, 2)
     df, pl = to_polars_api(df_raw, version="0.20")
     result = (
diff --git a/tpch/q4.py b/tpch/q4.py
index a79aa3c44..dc0d66847 100644
--- a/tpch/q4.py
+++ b/tpch/q4.py
@@ -13,7 +13,7 @@
 def q4(
     lineitem_ds_raw: Any,
     orders_ds_raw: Any,
-):
+) -> Any:
     var_1 = datetime(1993, 7, 1)
     var_2 = datetime(1993, 10, 1)
 
diff --git a/tpch/q5.py b/tpch/q5.py
index b0859b4e6..aa36ec87a 100644
--- a/tpch/q5.py
+++ b/tpch/q5.py
@@ -15,7 +15,7 @@ def q5(
     lineitem_ds_raw: Any,
     orders_ds_raw: Any,
     supplier_ds_raw: Any,
-):
+) -> Any:
     var_1 = "ASIA"
     var_2 = datetime(1994, 1, 1)
     var_3 = datetime(1995, 1, 1)