[GitHub] [spark] ueshin commented on a change in pull request #34354: [WIP][SPARK-37085][PYTHON][SQL] Add list/tuple overloads to array, struct, create_map, map_concat

[GitBox <gi...@apache.org>]

ueshin commented on a change in pull request #34354:
URL: https://github.com/apache/spark/pull/34354#discussion_r734744105



##########
File path: python/pyspark/sql/functions.py
##########
@@ -1652,7 +1652,19 @@ def expr(str: str) -> Column:
     return Column(sc._jvm.functions.expr(str))
 
 
+@overload
 def struct(*cols: "ColumnOrName") -> Column:
+    ...
+
+
+@overload
+def struct(__cols: Union[List["ColumnOrName"], Tuple["ColumnOrName", ...]]) -> Column:

Review comment:
       How about using more general type, like `Sequence` or `Iterable`?

##########
File path: python/pyspark/sql/functions.py
##########
@@ -1652,7 +1652,19 @@ def expr(str: str) -> Column:
     return Column(sc._jvm.functions.expr(str))
 
 
+@overload
 def struct(*cols: "ColumnOrName") -> Column:
+    ...
+
+
+@overload
+def struct(__cols: Union[List["ColumnOrName"], Tuple["ColumnOrName", ...]]) -> Column:
+    ...
+
+
+def struct(
+        *cols: Union["ColumnOrName", Union[List["ColumnOrName"], Tuple["ColumnOrName", ...]]]

Review comment:
       nit: style, 4-space indent?

##########
File path: python/pyspark/sql/functions.py
##########
@@ -1652,7 +1652,19 @@ def expr(str: str) -> Column:
     return Column(sc._jvm.functions.expr(str))
 
 
+@overload
 def struct(*cols: "ColumnOrName") -> Column:
+    ...
+
+
+@overload
+def struct(__cols: Union[List["ColumnOrName"], Tuple["ColumnOrName", ...]]) -> Column:

Review comment:
       Actually `List["ColumnOrName"]` is a bit tricky because `List` is not covariant and it doesn't accept `List[str]` or `List[Column]`.
   
   e.g.,
   
   ```
   % cat python/test.py
   from pyspark.sql import functions as F
   
   columns = ['a', 'b', 'c']
   reveal_type(columns)
   
   F.struct(columns)
   
   % mypy --config-file python/mypy.ini python/test.py
   python/test.py:4: note: Revealed type is "builtins.list[builtins.str*]"
   python/test.py:6: error: Argument 1 to "struct" has incompatible type "List[str]"; expected "Union[List[Union[Column, str]], Tuple[Union[Column, str], ...]]"  [arg-type]
   python/test.py:6: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
   python/test.py:6: note: Consider using "Sequence" instead, which is covariant
   ```
   
   whereas with `def struct(__cols: Sequence["ColumnOrName"]) -> Column:`:
   
   ```
   % mypy --config-file python/mypy.ini python/test.py
   python/test.py:4: note: Revealed type is "builtins.list[builtins.str*]"
   ```
   




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