Show me one of those times and I will show something else that works, not only as well, but better. Typographical programming is a subcategory of the practice of inventing another language to use in place of Smalltalk, and implementing in Smalltalk an interpreter for the other language. It helps think about and express the solution. However, the best way to do that is to use Smalltalk to express the concepts of the special language straightforwardly, with objects standing for the concepts, and using the message dispatch to implement the interpretation. That is easier to read and modify than using an interpretation by lots of explicit conditional tests, or by concatenating strings together, or representing something with the bits in an integer, say.
Encodings are for the external world, such as data stores and communication protocols.
A perfectly acceptable practice if used judiciously, according to James Robertson . There isn't a private language since it relies on a well known public one. It is true that browsing senders won't find it though and that might make it hard to find if you didn't know where to look. This is from memory. The original used a stream.