computer science

Gosling Emacs

Gosling Emacs is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Gosling Emacs rather than just read about it. In short: Gosling Emacs (often shortened to "Gosmacs" or "gmacs") is a discontinued Emacs implementation written in 1981 by James Gosling in C. Gosling initially allowed Gosling Emacs to be redistributed with no formal restrictions, as required by the "Emacs commune" since the 1970s, only asking for a letter acknowledging his authorship.

Key takeaways

Gosling Emacs belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Gosling Emacs to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gosling Emacs from memory before moving on to harder problems.

Reference excerpt

Gosling Emacs (often shortened to "Gosmacs" or "gmacs") is a discontinued Emacs implementation written in 1981 by James Gosling in C. Gosling initially allowed Gosling Emacs to be redistributed with no formal restrictions, as required by the "Emacs commune" since the 1970s, only asking for a letter acknowledging his authorship. Later, wishing to move on and after a failed search for people who would maintain it under the same rights, he finally sold his version of Emacs to UniPress because they agreed to sell it under reasonable terms. The dispute between Richard Stallman and UniPress inspired the creation of the first formal license for Emacs, which later became the GPL, as Congress had introduced copyright for software in 1980.

Features Gosling Emacs was especially noteworthy because of the effective redisplay code, which used a dynamic programming technique to solve the classical string-to-string correction problem. The algorithm was quite sophisticated; that section of the source was headed by a skull-and-crossbones in ASCII art, warning any would-be improver that even if they thought they understood how the display code worked, they probably did not.

Distribution Since Gosling had permitted its unrestricted redistribution, Richard Stallman used some Gosling Emacs code in the initial version of GNU Emacs. Among other things, he rewrote part of the Gosling code headed by the skull-and-crossbones comment and made it "...shorter, faster, clearer and more extensible." In 1983 UniPress began selling Gosling Emacs on Unix for $395 and on VMS for $2,500, marketing it as "EMACS–multi-window text editor (Gosling version)". Controversially, UniPress asked Stallman to stop distributing his version of Emacs for Unix. UniPress never took legal action against Stallman or his nascent Free Software Foundation, believing "hobbyists and academics could never produce an Emacs that could compete" with their product. All Gosling Emacs code was removed from GNU Emacs by version 16.56 (July 1985), with the possible exception of a few particularly involved sections of the display code. The latest versions of GNU Emacs (since August 2004) do not feature the skull-and-crossbones warning.

Extension language Its extension language, Mocklisp, has a syntax that appears similar to Lisp, but Mocklisp does not have lists, only strings and arrays. The Mocklisp interpreter, built by Gosling and a collaborator, was replaced by a full Lisp interpreter in GNU Emacs.

References

Christopher Kelty, "EMACS, grep, and UNIX: authorship, invention and translation in software", https://web.archive.org/web/20110728022656/http://www.burlingtontelecom.net/~ashawley/gnu/emacs/ConText-Kelty.pdf

Worked examples

Example 1 — a first encounter with Gosling Emacs

Start with the simplest possible case. Write down what Gosling Emacs claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Gosling Emacs before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Gosling Emacs ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Gosling Emacs

In research: Gosling Emacs appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Gosling Emacs in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Gosling Emacs is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1981 software, Emacs, Unix text editors, so understanding it makes those chapters shorter.
In everyday life: Look for Gosling Emacs outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Gosling Emacs in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gosling Emacs means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Gosling Emacs out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gosling Emacs in simple terms?

Why does Gosling Emacs matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Gosling Emacs?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Gosling Emacs.