1. A computer readable storage medium comprising: a language component for causing a computer to receive a user input expression comprising comprehension notations by specifying a user-definable type or class as part of a generalized comprehension that appears as an outside operator to a fixed or static comprehension, enabling programming of comprehension notations in the imperative language; an interface component for causing the computer to describe a meaning of the comprehension by associating the user-definable type or class with an interface that implements the class, defining methods for the interface in order to supply desired functionality for the class, and by applying the class and associated interface in an exterior manner to a list or fixed comprehension function; and a translation component for causing the computer to analyze the meaning of the comprehension notations and facilitates execution of the comprehension notations in accordance with the imperative language.