A method and computer program product for detecting and diagnosing errors in a generic function call and then presenting them in an error message is disclosed. A generic function call is provided for evaluation. A corresponding generic function definition containing sets of dummy arguments that define arguments signatures for associated specific functions is also provided. In a first sorting the generic function call is compared with the argument signatures to determine whether the generic function call contains errors. A second sorting is then used to determine the nature of the errors. An error message describing the nature of the errors is then generated.