Topic summary
Abstract data structure
Extracted from the Wikipedia article Abstract data type.
Axiomatic semantics
In the spirit of functional programming, each state of an abstract data structure is a separate entity or value. In this view, each operation is modelled as a mathematical function with no side effects. Operations that modify the ADT are modeled as functions that take the old state as an argument and returns the new state as part of the result. The order in which operations are evaluated is immaterial, and the same operation applied to the same arguments (including the same input states) will always return the same results (and output states). The constraints are specified as axioms or algebraic laws that the operations must satisfy.