In formal semantics, researchers assign meanings to sentences of a natural language. This work is guided by the principle of compositionality: the meaning of an expression is a function of the meanings of its parts. These functions are often formalized using the [lambda]-calculus. However, there are areas of language which challenge the notion of compositionality, e.g. anaphoric pronouns or presupposition triggers. These force researchers to either abandon compositionality or adjust the structure of meanings. In the first case, meanings are derived by processes that no longer correspond to pure mathematical functions but rather to context-sensitive procedures, much like the functions of a programming language that manipulate their context w...