AsTeR has been presented as a system for rendering documents in audio. More generally, AsTeR is a system for speaking structured information. This fact is amply demonstrated by the following example, where we interface AsTeR to the Emacs calculator.
The Emacs calculator, a public domain symbolic algebra system, provides an excellent source of examples for trying out the variable-substitution rendering style. Creating such an audio interface could be challenging, since the expressions produced are quite complex. However, the flexible design of AsTeR and the power of Emacs makes this interface easy. A collection of Emacs Lisp functions encodes the calculator output in LaTeX and places it in an Emacs buffer, which AsTeR then renders.
A user of the Emacs calculator can execute command read-previous-calc-answer to have the output rendered by AsTeR . The expression can be browsed, summarized, transformed by applying variable substitution, and rendered in any of the ways described in the context of documents.