add time to infer from literal & api

ibis/expr/api.py

@@ -59,7 +59,8 @@
 
 
 __all__ = [
-    'schema', 'table', 'literal', 'expr_list', 'timestamp',
+    'schema', 'table', 'literal', 'expr_list',
+    'timestamp', 'time',
     'case', 'where', 'sequence',
     'now', 'desc', 'null', 'NA',
     'cast', 'coalesce', 'greatest', 'least',
@@ -174,6 +175,24 @@ def timestamp(value):
     return ir.TimestampScalar(ir.literal(value).op())
 
 
+def time(value):
+    """
+    Returns a time literal if value is likely coercible to a time
+
+    Parameters
+    ----------
+    value : time value as string
+
+    Returns
+    --------
+    result : TimeScalar
+    """
+    if isinstance(value, six.string_types):
+        from pandas.core.tools.datetimes import to_time
+        value = to_time(value)
+    return ir.TimeScalar(ir.literal(value).op())
+
+
 schema.__doc__ = """\
 Validate and return an Ibis Schema object
 

ibis/expr/tests/test_value_exprs.py

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 import operator
-from datetime import date, datetime
+from datetime import date, datetime, time
 
 import pytest
 
@@ -905,3 +905,53 @@ def test_decimal_modulo_output_type(value, type, expected_type_class):
     t = ibis.table([('a', type)])
     expr = t.a % value
     assert isinstance(expr.type(), expected_type_class)
+
+
+@pytest.mark.parametrize(
+    ('left', 'right'),
+    [
+        (literal('10:00'), time(10, 0)),
+        (time(10, 0), literal('10:00')),
+    ]
+)
+@pytest.mark.parametrize(
+    'op',
+    [
+        operator.eq,
+        operator.ne,
+        operator.lt,
+        operator.le,
+        operator.gt,
+        operator.ge,
+        lambda left, right: ibis.time(
+            '10:00'
+        ).between(left, right),
+    ]
+)
+def test_time_compare(op, left, right):
+    result = op(left, right)
+    assert result.type().equals(dt.boolean)
+
+
+@pytest.mark.parametrize(
+    ('left', 'right'),
+    [
+        (literal('10:00'), date(2017, 4, 2)),
+        (literal('10:00'), datetime(2017, 4, 2, 1, 1)),
+        (literal('10:00'), literal('2017-04-01')),
+        (time(10, 0), literal('2017-04-01')),
+    ]
+)
+@pytest.mark.parametrize(
+    'op',
+    [
+        operator.eq,
+        operator.lt,
+        operator.le,
+        operator.gt,
+        operator.ge,
+        ]
+)
+def test_time_timestamp_invalid_compare(op, left, right):
+    result = op(left, right)
+    assert result.type().equals(dt.boolean)

ibis/expr/types.py

@@ -536,6 +536,8 @@ def infer_literal_type(value):
         return dt.timestamp
     elif isinstance(value, datetime.date):
         return dt.date
+    elif isinstance(value, datetime.time):
+        return dt.time
     elif isinstance(value, list):
         return dt.Array(rules.highest_precedence_type(
             list(map(literal, value))