>I'm not in a different domain; The "domain" doesn't have to necessarily mean different disciplines such as "game programming" is one domain and "online shoppi

>I'm not in a different domain; The "domain" doesn't have to necessarily mean different disciplines such as "game programming" is one domain and "online shopping" is another domain. Thanks to montrose's reminder, I cite PG's "On Lisp" page 5 (which appears immediately after the "Programming Bottom-Up" section): >We transform our software from a mere program into a _programming language_, and advanced users can build upon it the extra features that they need. [...] The simplest bottom-up programs consist of two layers: language and program. Complex programs may be written as a series of layers, each one acting as a programming language for the one above. If this philosophy is carried all the way up to the topmost layer, that layer becomes a programming language for the user. Also in section "1.4 Extending Lisp" page 7: >Lisp is an excellent language for writing compilers and interpreters, but it offers another way of defining a new language which is often more elegant and certainly much less work: to define the new language as a modification of Lisp. Then the parts of Lisp which can appear unchanged in the new language (e.g. arithmetic or I/O) can be used as is, and you only have to implement the parts which are different (e.g. control structure). A language implemented in this way is called an _embedded language_. Embedded languages are a natural outgrowth of bottom-up programming. Yes, the 1993 time period predates today's "DSL" meme but now that "DSL" has permeated into widespread programmers' awareness, is there a better label to describe those PG paragraphs? I argue that today, people would rewrite PGs technique in their mind as "layering DSLs".