Tom Lord was the first to fully concentrate his efforts on an embeddable language runtime, which he named “GEL”, the GNU Extension Language.
GEL was the product of converting SCM, Aubrey Jaffer’s implementation of Scheme, into something more appropriate to embedding as a library. (SCM was itself based on an implementation by George Carrette, SIOD.)
Lord managed to convince Richard Stallman to dub GEL the official extension language for the GNU project. It was a natural fit, given that Scheme was a cleaner, more modern Lisp than Emacs Lisp. Part of the argument was that eventually when GEL became more capable, it could gain the ability to execute other languages, especially Emacs Lisp.
Due to a naming conflict with another programming language, Jim Blandy suggested a new name for GEL: “Guile”. Besides being a recursive acronym, “Guile” craftily follows the naming of its ancestors, “Planner”, “Conniver”, and “Schemer”. (The latter was truncated to “Scheme” due to a 6-character file name limit on an old operating system.) Finally, “Guile” suggests “guy-ell”, or “Guy L. Steele”, who, together with Gerald Sussman, originally discovered Scheme.
Around the same time that Guile (then GEL) was readying itself for public release, another extension language was gaining in popularity, Tcl. Many developers found advantages in Tcl because of its shell-like syntax and its well-developed graphical widgets library, Tk. Also, at the time there was a large marketing push promoting Tcl as a “universal extension language”.
Richard Stallman, as the primary author of GNU Emacs, had a particular vision of what extension languages should be, and Tcl did not seem to him to be as capable as Emacs Lisp. He posted a criticism to the comp.lang.tcl newsgroup, sparking one of the internet’s legendary flamewars. As part of these discussions, retrospectively dubbed the “Tcl Wars”, he announced the Free Software Foundation’s intent to promote Guile as the extension language for the GNU project.
It is a common misconception that Guile was created as a reaction to Tcl. While it is true that the public announcement of Guile happened at the same time as the “Tcl wars”, Guile was created out of a condition that existed outside the polemic. Indeed, the need for a powerful language to bridge the gap between extension of existing applications and a more fully dynamic programming environment is still with us today.