[FEAT]: allow for implicit coercion between str & date (#3337)

src/daft-core/src/datatypes/infer_datatype.rs

@@ -128,6 +128,11 @@ impl<'a> InferDataType<'a> {
 
                 Ok((DataType::Boolean, Some(d_type.clone()), d_type))
             }
+
+            (DataType::Utf8, DataType::Date) | (DataType::Date, DataType::Utf8) => {
+                // Date is logical, so we cast to intermediate type (date), then compare on the physical type (i32)
+                Ok((DataType::Boolean, Some(DataType::Date), DataType::Int32))
+            }
             (s, o) if s.is_physical() && o.is_physical() => {
                 Ok((DataType::Boolean, None, try_physical_supertype(s, o)?))
             }

tests/dataframe/test_temporals.py

@@ -2,7 +2,7 @@
 
 import itertools
 import tempfile
-from datetime import datetime, timedelta, timezone
+from datetime import date, datetime, timedelta, timezone
 
 import pyarrow as pa
 import pytest
@@ -465,3 +465,20 @@ def test_intervals(op, expected):
     expected = {"datetimes": expected}
 
     assert actual == expected
+
+
+@pytest.mark.parametrize(
+    "value",
+    [
+        date(2020, 1, 1),  # explicit date
+        "2020-01-01",  # implicit coercion
+    ],
+)
+def test_date_comparison(value):
+    date_df = daft.from_pydict({"date_str": ["2020-01-01", "2020-01-02", "2020-01-03"]})
+    date_df = date_df.with_column("date", col("date_str").str.to_date("%Y-%m-%d"))
+    actual = date_df.filter(col("date") == value).select("date").to_pydict()
+
+    expected = {"date": [date(2020, 1, 1)]}
+
+    assert actual == expected

tests/sql/test_temporal_exprs.py

@@ -88,3 +88,11 @@ def test_extract():
     """).collect()
 
     assert actual.to_pydict() == expected.to_pydict()
+
+
+def test_date_comparison():
+    date_df = daft.from_pydict({"date_str": ["2020-01-01", "2020-01-02", "2020-01-03"]})
+    date_df = date_df.with_column("date", daft.col("date_str").str.to_date("%Y-%m-%d"))
+    expected = date_df.filter(daft.col("date") == "2020-01-01").select("date").to_pydict()
+    actual = daft.sql("select date from date_df where date == '2020-01-01'").to_pydict()
+    assert actual == expected