def infer_and_cast(value: Any):
    """
    In some cases we'll be feeding params dicts to functions we don't own;
    for example, PyTorch optimizers. In that case we can't use `pop_int`
    or similar to force casts (which means you can't specify `int` parameters
    using environment variables). This function takes something that looks JSON-like
    and recursively casts things that look like (bool, int, float) to (bool, int, float).
    """

    if isinstance(value, (int, float, bool)):
        # Already one of our desired types, so leave as is.
        return value
    elif isinstance(value, list):
        # Recursively call on each list element.
        return [infer_and_cast(item) for item in value]
    elif isinstance(value, dict):
        # Recursively call on each dict value.
        return {key: infer_and_cast(item) for key, item in value.items()}
    elif isinstance(value, str):
        # If it looks like a bool, make it a bool.
        if value.lower() == "true":
            return True
        elif value.lower() == "false":
            return False
        else:
            # See if it could be an int.
            try:
                return int(value)
            except ValueError:
                pass
            # See if it could be a float.
            try:
                return float(value)
            except ValueError:
                # Just return it as a string.
                return value
    else:
        raise ValueError(f"cannot infer type of {value}")
In some cases we'll be feeding params dicts to functions we don't own;
for example, PyTorch optimizers. In that case we can't use `pop_int`
or similar to force casts (which means you can't specify `int` parameters
using environment variables). This function takes something that looks JSON-like
and recursively casts things that look like (bool, int, float) to (bool, int, float).
allennlp/common/params.py