Fixed issue with boolean outputs

dspy/functional/functional.py

@@ -119,7 +119,22 @@ def _prepare_signature(self) -> dspy.Signature:
             is_output = field.json_schema_extra["__dspy_field_type"] == "output"
             type_ = field.annotation
             if is_output:
-                if type_ in (str, int, float, bool):
+                if type_ is bool:
+
+                    def parse(x):
+                        x = x.strip().lower()
+                        if x not in ("true", "false"):
+                            raise ValueError("Respond with true or false")
+                        return x == "true"
+
+                    signature = signature.with_updated_fields(
+                        name,
+                        desc=field.json_schema_extra.get("desc", "")
+                        + (" (Respond with true or false)" if type_ != str else ""),
+                        format=lambda x: x if isinstance(x, str) else str(x),
+                        parser=parse,
+                    )
+                elif type_ in (str, int, float, bool):
                     signature = signature.with_updated_fields(
                         name,
                         desc=field.json_schema_extra.get("desc", "")

tests/functional/test_functional.py

@@ -653,6 +653,28 @@ def space_in_a(cls, a: str) -> str:
     _ = ValidatedSignature(a="with space")
 
 
+def test_lm_as_validator():
+    @predictor
+    def is_square(n: int) -> bool:
+        """Is n a square number?"""
+
+    def check_square(n):
+        assert is_square(n=n)
+        return n
+
+    @predictor
+    def next_square(n: int) -> Annotated[int, AfterValidator(check_square)]:
+        """What is the next square number after n?"""
+
+    lm = DummyLM(["3", "False", "4", "True"])
+    dspy.settings.configure(lm=lm)
+
+    m = next_square(n=2)
+    lm.inspect_history(n=2)
+
+    assert m == 4
+
+
 def test_annotated_validator():
     def is_square(n: int) -> int:
         root = n**0.5
@@ -692,3 +714,70 @@ def next_square(n: int) -> Annotated[int, AfterValidator(is_square)]:
     lm.inspect_history(n=2)
 
     assert m == 4
+
+
+def test_demos():
+    demos = [
+        dspy.Example(input="What is the speed of light?", output="3e8"),
+    ]
+    program = LabeledFewShot(k=len(demos)).compile(
+        student=dspy.TypedPredictor("input -> output"),
+        trainset=[ex.with_inputs("input") for ex in demos],
+    )
+
+    lm = DummyLM(["Paris"])
+    dspy.settings.configure(lm=lm)
+
+    assert program(input="What is the capital of France?").output == "Paris"
+
+    assert lm.get_convo(-1) == textwrap.dedent("""\
+        Given the fields `input`, produce the fields `output`.
+
+        ---
+
+        Follow the following format.
+
+        Input: ${input}
+        Output: ${output}
+
+        ---
+
+        Input: What is the speed of light?
+        Output: 3e8
+
+        ---
+
+        Input: What is the capital of France?
+        Output: Paris""")
+
+
+def _test_demos_missing_input():
+    demos = [dspy.Example(input="What is the speed of light?", output="3e8")]
+    program = LabeledFewShot(k=len(demos)).compile(
+        student=dspy.TypedPredictor("input -> output, thoughts"),
+        trainset=[ex.with_inputs("input") for ex in demos],
+    )
+    dspy.settings.configure(lm=DummyLM(["My thoughts", "Paris"]))
+    assert program(input="What is the capital of France?").output == "Paris"
+
+    assert dspy.settings.lm.get_convo(-1) == textwrap.dedent("""\
+        Given the fields `input`, produce the fields `output`.
+
+        ---
+
+        Follow the following format.
+
+        Input: ${input}
+        Thoughts: ${thoughts}
+        Output: ${output}
+
+        ---
+
+        Input: What is the speed of light?
+        Output: 3e8
+
+        ---
+
+        Input: What is the capital of France?
+        Thoughts: My thoughts
+        Output: Paris""")