User:Mabloom/sandbox

As a programming language
The obscurity of the TECO programming language is well-described in the following quote from "Real Programmers Don't Use PASCAL", a letter from Ed Post to Datamation, July 1983:

"It has been observed that a TECO command sequence more closely resembles transmission line noise than readable text. One of the more entertaining games to play with TECO is to type your name in as a command line and try to guess what it does. Just about any possible typing error while talking with TECO will probably destroy your program, or even worse - introduce subtle and mysterious bugs in a once working subroutine."

According to Craig Finseth, author of The Craft of Text Editing: Emacs for the Modern World, TECO could be considered to be one of the first "write-only" languages. That is, it could be argued that once a program is written in TECO, it would be extremely difficult to comprehend what it did without appropriate documentation.

Despite the odd syntax, the TECO command language was tremendously powerful, and clones are still available for MS-DOS and for Unix.

TECO commands are characters (including control-characters), and the prompt is a single asterisk: *

The escape key displays as a dollar sign, pressed once it delineates the end of a command requiring an argument and pressed twice initiates the execution of the entered command(s): *$$