feat(api): support deferred objects in literal

ibis/expr/types/generic.py

@@ -2427,6 +2427,7 @@ def null(type: dt.DataType | str | None = None) -> Value:
 
 
 @public
+@deferrable
 def literal(value: Any, type: dt.DataType | str | None = None) -> Scalar:
     """Create a scalar expression from a Python value.
 

ibis/tests/expr/test_literal.py

@@ -8,6 +8,7 @@
 
 import ibis
 import ibis.expr.datatypes as dt
+from ibis import _
 from ibis.common.collections import frozendict
 from ibis.expr.operations import Literal
 from ibis.tests.util import assert_pickle_roundtrip
@@ -166,3 +167,11 @@ def test_timestamp_literal_without_tz():
 def test_integer_as_decimal():
     lit = ibis.literal(12, type="decimal")
     assert lit.op().value == decimal.Decimal(12)
+
+
+def test_deferred(table):
+    expr = _.g.get_name()
+    dtype = _.g.type()
+    deferred = ibis.literal(expr, type=dtype)
+    result = deferred.resolve(table)
+    assert result.op().value == "g"

ibis/tests/test_strategies.py

@@ -4,12 +4,10 @@
 import hypothesis.strategies as st
 import pytest
 
-import ibis
 import ibis.expr.datatypes as dt
 import ibis.expr.schema as sch
 import ibis.expr.types as ir
 import ibis.tests.strategies as its
-from ibis.common.annotations import ValidationError
 
 
 @h.given(its.null_dtype)
@@ -173,10 +171,4 @@ def test_memtable(memtable):
     assert isinstance(memtable.schema(), sch.Schema)
 
 
-@h.given(its.all_dtypes())
-def test_deferred_literal(dtype):
-    with pytest.raises(ValidationError):
-        ibis.literal(ibis._.a, type=dtype)
-
-
 # TODO(kszucs): we enforce field name uniqueness in the schema, but we don't for Struct datatype