The Evolution of Emacs from TECO to Emacs Lisp

Emacs, the powerful text editing software, has a rich history that spans decades. This journey has seen the language it used for its core functionalities evolve over time. This article will explore the early days of Emacs, from its inception using TECO to its eventual transition to Emacs Lisp, and the important languages that played a part in this evolution, such as Mocklisp.

Early Beginnings: TECO Ephemeral Emacs

Interestingly, Emacs did not begin as we know it today. The earliest version of Emacs, often referred to as ‘Ephemeral Emacs’, was written using TECO, a text editor widely used in the 1970s and 1980s. TECO, which stands for Text Editor and COrrector, was a powerful and flexible editor that many early text editors were based on. Being a macro language, TECO allowed users to write and run macros that essentially became miniature editors within the editor, streamlining the editing process. However, this early implementation had limitations and was not as sophisticated as what Emacs has become known for today.

The Introduction of Mocklisp

The transition from TECO to a more sophisticated language began with the work of James Gosling. Gosling, then a graduate student at Carnegie Mellon University, played a crucial role in the development of Unix Emacs. The first appearance of a Lisp dialect in Emacs originated as a pun on the name “Maclisp”. Maclisp, a variant of LISP, was a significant dialect of Lisp that gained popularity in its time, especially at MIT and CMU.

James Gosling developed a dialect of Lisp that he called “Mocklisp”. This pun not only humorously referenced Maclisp but also indicated that it was a mock or experimental version, suggesting that it was a step towards the eventual adoption of a more robust and feature-rich language. Mocklisp served as a bridge, showing the community that Emacs could be extended beyond simple text manipulation to include more complex functionality.

GNU Emacs and the GNU Project

The development of Emacs for Unix systems using Mocklisp was significant, but it was not the end of its evolution. GNU Emacs, a variant of Emacs developed by Richard Stallman for the GNU project, took Emacs to new heights. According to an interview with James Gosling, Ghuillem Potiotine, a French computer scientist, noted that when Richard Stallman worked on bringing Emacs to freedom, he "stole" it from Gosling and others, effectively liberating it for further development under the GNU General Public License (GPL).

The transition from Mocklisp to Emacs Lisp was a natural progression for several reasons. First, Emacs Lisp was designed to be more powerful and flexible than Mocklisp, offering a more robust environment for scripting and customization. Second, Emacs Lisp was better suited to the complex operations required for a text editor like Emacs, allowing for more sophisticated modes and extensions. This transition marked the birth of a new era in Emacs development, where the editor could be easily extended and customized by users and developers alike.

Conclusion

The journey of Emacs from its humble beginnings using TECO to the advanced text editor known worldwide today, illustrates the importance of language evolution in software development. The evolution from TECO to Mocklisp and finally to Emacs Lisp demonstrates the iterative process of improvement and adaptation that led to the powerful and flexible editor we use today. Understanding this history can provide valuable insights into both the development of software and the role of language in shaping our digital world.