EvalFn

API reference for EvalFn

EvalFn

EvalFn

Evaluator that wraps a user-provided function for dynamic evaluation.

This class allows users to create evaluators from any callable function, automatically handling parameter passing, validation, and result conversion to Score objects.

Key Features:

• Dynamic Function Wrapping: Converts any callable into an evaluator

• Argument Validation: Validates that provided arguments match function signature

• Smart Result Conversion: Automatically converts various return types to Score

• Error Handling: Gracefully handles function execution and argument errors

• Parameter Flexibility: Supports functions with any parameter signature

Parameters

Parameter	Type	Required	Default	Description
fn	Callable	✗	None	The callable function to wrap as an evaluator.
score_name	str | None	✗	None	Optional custom name for the score. If not provided, uses the function name.

Example

EvalFn

EvalFn

Evaluator that wraps a user-provided function for dynamic evaluation.

This class allows users to create evaluators from any callable function, automatically handling parameter passing, validation, and result conversion to Score objects.

Key Features:

• Dynamic Function Wrapping: Converts any callable into an evaluator

• Argument Validation: Validates that provided arguments match function signature

• Smart Result Conversion: Automatically converts various return types to Score

• Error Handling: Gracefully handles function execution and argument errors

• Parameter Flexibility: Supports functions with any parameter signature

Parameters

Parameter	Type	Required	Default	Description
fn	Callable	✗	None	The callable function to wrap as an evaluator.
score_name	str | None	✗	None	Optional custom name for the score. If not provided, uses the function name.

Example

>>> def equals(a, b):
    ...     return a == b
    >>>
    >>> evaluator = EvalFn(equals, score_name="exact_match")
    >>> score = evaluator.score(a="hello", b="hello")
    >>> print(score.value)  # 1.0
    >>>
    >>> def length_check(text, min_length=5):
        ...     return len(text) >= min_length
        >>>
        >>> evaluator = EvalFn(length_check)
        >>>
        >>> # Invalid arguments raise TypeError
        >>> try:
            ...     evaluator.score(wrong_param="value")
            ... except TypeError as e:
                ...     print(f"Error: {e}")

#### *property* name *: str*

#### score()

Execute the wrapped function and convert result to Score.

Calls the wrapped function with the provided arguments and converts
the result to a Score object. Validates that the provided arguments
match the function’s signature.

#### Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| `*args` | `Any` | ✗ | `None` | Positional arguments to pass to the wrapped function. |

#### Returns
A Score object representing the function’s evaluation result.
**Return type:** Score

#### Raises
**TypeError** – If the provided arguments don’t match the function signature.

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The function result is converted to a Score as follows:
- bool: 1.0 for True, 0.0 for False
- int/float: Direct value conversion
- Score: Returns as-is

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