feat: add to_json convenience API

README.md

@@ -81,6 +81,13 @@ print(toons.dumps(user))
 # name: Bob
 # age: 25
 # active: true
+
+# Convert TOON to JSON
+print(toons.to_json("name: Alice\nage: 30", indent=2))
+# {
+#   "name": "Alice",
+#   "age": 30
+# }
 ```
 
 ### File Operations

src/lib.rs

@@ -45,6 +45,7 @@ pyo3::create_exception!(
 #[pyo3::pymodule]
 mod toons {
     use pyo3::prelude::*;
+    use pyo3::types::PyDict;
 
     #[allow(non_upper_case_globals)]
     #[pymodule_export]
@@ -89,6 +90,53 @@ mod toons {
         crate::deserialization::deserialize(py, &s, strict, expand_mode, indent)
     }
 
+    /// Convert a TOON formatted string to a JSON formatted string.
+    ///
+    /// Parse a string containing TOON (Token-Oriented Object Notation) data
+    /// and return the corresponding JSON string using Python's standard
+    /// library json module.
+    ///
+    /// Args:
+    ///     s: A string containing TOON formatted data
+    ///     strict: If True (default), enforce strict TOON v3.0 compliance.
+    ///             If False, allow some leniency (e.g. blank lines in arrays).
+    ///     expand_paths: Path expansion mode: None, "off", "safe", "always".
+    ///     indent: Number of spaces per JSON indentation level, or None for
+    ///             compact JSON (default: 2)
+    ///
+    /// Returns:
+    ///     A string containing JSON decoded from the TOON string
+    ///
+    /// Raises:
+    ///     ToonDecodeError: If the input is malformed. See `loads` for details.
+    ///
+    /// Example:
+    ///     >>> import toons
+    ///     >>> json_str = toons.to_json("name: Alice\nage: 30")
+    ///     >>> print(json_str)
+    ///     {
+    ///       "name": "Alice",
+    ///       "age": 30
+    ///     }
+    #[pyfunction]
+    #[pyo3(signature = (s, *, strict=true, expand_paths=None, indent=None))]
+    fn to_json(
+        py: Python,
+        s: String,
+        strict: bool,
+        expand_paths: Option<&str>,
+        indent: Option<usize>,
+    ) -> PyResult<String> {
+        let expand_mode = expand_paths.unwrap_or("off");
+        let parsed_obj = crate::deserialization::deserialize(py, &s, strict, expand_mode, None)?;
+        let json = py.import("json")?;
+        let kwargs = PyDict::new(py);
+        kwargs.set_item("indent", indent)?;
+        json.getattr("dumps")?
+            .call((parsed_obj,), Some(&kwargs))?
+            .extract()
+    }
+
     /// Deserialize a TOON formatted file to a Python object.
     ///
     /// Read TOON data from a file-like object and return the corresponding

tests/integration/test_to_json.py

@@ -0,0 +1,53 @@
+import json
+
+import pytest
+
+import toons
+
+
+class TestToJson:
+    """Integration tests for to_json() function."""
+
+    def test_to_json_uses_json_default_behavior(self):
+        """to_json() matches json.dumps() default behavior."""
+        toon_str = "name: Alice\nage: 30\ntags[2]: admin,user"
+        result = toons.to_json(toon_str)
+
+        assert result == json.dumps(
+            {"name": "Alice", "age": 30, "tags": ["admin", "user"]}
+        )
+
+    def test_to_json_accepts_indent_none(self):
+        """to_json() passes indent=None through to json.dumps()."""
+        toon_str = "name: Alice\nage: 30"
+        result = toons.to_json(toon_str, indent=None)
+
+        assert result == json.dumps({"name": "Alice", "age": 30}, indent=None)
+
+    def test_to_json_accepts_custom_indent(self):
+        """to_json() passes custom indent through to json.dumps()."""
+        toon_str = "name: Alice\nage: 30"
+        result = toons.to_json(toon_str, indent=2)
+
+        assert result == json.dumps(
+            {"name": "Alice", "age": 30},
+            indent=2,
+        )
+
+    def test_to_json_respects_strict_flag(self):
+        """to_json() forwards strict=False to the TOON parser."""
+        toon_str = "[3]:\n  - 1\n\n  - 2\n  - 3"
+        result = toons.to_json(toon_str, strict=False)
+
+        assert result == json.dumps([1, 2, 3])
+
+    def test_to_json_raises_decode_error(self):
+        """to_json() raises ToonDecodeError for malformed TOON."""
+        with pytest.raises(toons.ToonDecodeError):
+            toons.to_json("a:\n  b:\n     c: 1\n")
+
+    def test_to_json_respects_expand_paths(self):
+        """to_json() forwards expand_paths to the TOON parser."""
+        result = toons.to_json("user.name: Alice", expand_paths="safe")
+
+        assert result == json.dumps({"user": {"name": "Alice"}})

toons.pyi

@@ -75,6 +75,30 @@ def loads(
     """
     ...
 
+def to_json(
+    s: str,
+    *,
+    strict: bool = True,
+    expand_paths: Optional[str] = None,
+    indent: Optional[int] = None,
+) -> str:
+    """Convert a TOON string to a JSON string.
+
+    Args:
+        s: TOON-formatted string.
+        strict: Enforce strict TOON v3.0 compliance.
+        expand_paths: Path expansion mode: None, "off", "safe", "always".
+        indent: Spaces per JSON indentation level, or None for compact JSON.
+
+    Returns:
+        JSON-formatted string.
+
+    Raises:
+        ToonDecodeError: If the input is malformed. Subclass of ValueError;
+            carries structured ``.line`` and ``.source`` attributes.
+    """
+    ...
+
 def dump(
     obj: Any,
     fp: IO[str],