A Glimpse of Paradise

Having understood that most attractive programming paradigms introduced recently in declarative symbolic programming languagesneed not be provided at the detriment of one another, we also believe that they can and should coexist with the more conventional state-effecting style of explicit control and data processing of imperative programming. To this end, we language designers must provide three primeval abstractions which could allow retrieving of most particular programming styles as particular instances, with the additional freedom of manipulating these abstractions explicitly. In the next decade, computer programming should allow specifying (1) abstract data structures, (2) abstract control structures, and (3) abstract constraint structures. With these basic ideas in mind, we shall propose and sketch a specific design for a language and lay out some explicit requirements. Doing so, we shall try to compare this attempt to the state of the art. It is true, that as the form often does not accord with the intention of the art, because the material is deaf to respond, so the creature sometimes deviates from due course; ... Dante Alighieri The Divine Comedy—Paradise, Canto I:121