mathematics

OBJ (programming language)

OBJ (programming language) is a mathematics 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 OBJ (programming language) rather than just read about it. In short: OBJ is a programming language family introduced by Joseph Goguen in 1976, and further worked on by Jose Meseguer. Overview It is a family of declarative "ultra high-level" languages.

Key takeaways

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

Reference excerpt

OBJ is a programming language family introduced by Joseph Goguen in 1976, and further worked on by Jose Meseguer.

Overview It is a family of declarative "ultra high-level" languages. It features abstract types, generic modules, subsorts (subtypes with multiple inheritance), pattern-matching modulo equations, E-strategies (user control over laziness), module expressions (for combining modules), theories and views (for describing module interfaces) for the massively parallel RRM (rewrite rule machine). Members of the OBJ family of languages include CafeOBJ, Eqlog, FOOPS, Kumo, Maude, OBJ2, and OBJ3.

OBJ2 OBJ2 is a programming language with Clear-like parametrised modules and a functional system based on equations.

OBJ3 OBJ3 is a version of OBJ based on order-sorted rewriting. OBJ3 is agent-oriented and runs on Kyoto Common Lisp AKCL.

See also Automated theorem proving Comparison of programming languages Formal methods

References

J. A. Goguen, Higher-Order Functions Considered Unnecessary for Higher-Order Programming. In Research Topics in Functional Programming (June 1990). pp. 309–351. "Principles of OBJ2", K. Futatsugi et al., 12th POPL, ACM 1985, pp. 52–66. J. A. Goguen; T. Winkler; J. Meseguer; K. Futatsugi; J.-P. Jouannaud (2000), "Introducing OBJ", in J. A. Goguen; G. Malcolm (eds.), Software Engineering with OBJ: Algebraic Specification in Action, Springer Science+Business Media, New York, NY, pp. 3–167, ISBN 978-1-4757-6541-0

External links The OBJ archive The OBJ family Information and OBJ3 manual, PostScript format

Worked examples

Example 1 — a first encounter with OBJ (programming language)

Start with the simplest possible case. Write down what OBJ (programming language) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 OBJ (programming language) 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 OBJ (programming language) 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 OBJ (programming language)

In research: OBJ (programming language) appears in mathematics 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 OBJ (programming language) 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: OBJ (programming language) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Academic programming languages, Formal specification languages, Functional languages, so understanding it makes those chapters shorter.
In everyday life: Look for OBJ (programming language) 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 OBJ (programming language) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OBJ (programming language) 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 OBJ (programming language) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OBJ (programming language) in simple terms?

OBJ is a programming language family introduced by Joseph Goguen in 1976, and further worked on by Jose Meseguer. Overview It is a family of declarative "ultra high-level" languages.

Why does OBJ (programming language) matter?

Because it connects several mathematics 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 OBJ (programming language)?

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 OBJ (programming language).