Metalinguistic abstraction

<h2 id="explanation">Explanation</h2>
<p>For example, consider modelling an airport inside a computer. The airport has elements like passengers, bookings, employees, budgets, planes, luggage, arrivals and departures, and transit services.
</p><p>A <a href="/facts/Procedural_language/7r5xz7kx">procedural</a> (e.g. <a href="/facts/C_(programming_language)/Ky2No763">C</a>) programmer might create data structures to represent these elements of an airport and procedures or routines to operate on those data structures and update them, modelling the airport as a series of processes undergone by its various elements. E.g., bookings is a database used to keep passengers and planes synchronised via updates logged as arrivals and departures, budgets are similar but for money: airports  are a lot of things that need to get done in the right order to see that passengers get where they're going.
</p><p>An <a href="/facts/Object-oriented/TxNMEcao">object-oriented</a> (e.g. <a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a>) programmer might create <a href="/facts/Object_(computer_science)/eX99dtAw">objects</a> to represent the elements of the airport with <a href="/facts/Method_(computer_science)/8kAXxVYs">methods</a> which represent their behaviors, modelling the airport as a collection of possibly related things which characteristically interact with each other. E.g., passengers, employees, and planes possess location attributes which can be modified via applicable transit methods: transit services have methods to bring employees and passengers to and from airports, planes have methods to bring passengers along with themselves between different airports: airports are a grouping of things working together as intended.
</p><p>A <a href="/facts/Functional_programming/cdxqPEIM">functional</a> (e.g. <a href="/facts/Scheme_(programming_language)/0aGdf3SC">Scheme</a>) programmer might create <a href="/facts/Higher-order_function/VjnjGbpt">higher-order functions</a> representing both the elements and behaviors or processes of the airport, modelling the airport as a map of relations between elements in its various domains and those in their assorted codomains. E.g., airports map budgets to bookings schedules, each of which is itself a map of elements to elements: balances of income and expenditure, and balances of arrivals and departures, each of which is, recursively, its own mapping of elements and their own mappings in kind, collectively comprising a set of morphisms: airports are, transitively, the evaluative transformation of a certain spacetime economy.
</p><p>Finally, a metalinguistic programmer might abstract the problem by creating new <a href="/facts/Domain-specific_language/n18H1foD">domain-specific languages</a> for modelling airports, with peculiar <a href="/facts/Primitive_(computer_science)/0c898228">primitives</a> and <a href="/facts/Type_(computer_science)/fcx5hgVL">types</a> for doing so. The new language could encompass any or all of the above approaches where most suitable,<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> potentially enabling the programmer to retain both the abstract generality of the functional model, the intuitive sensibility of the object model, and the detail-driven pragmatism of the procedural model.
</p><p>Because the creation of <a href="/facts/Functional_programming/cdxqPEIM">functional</a> metalinguistic abstractions in <a href="/facts/Imperative_programming/6b5dUnE1">non-functional</a> languages can be cumbersome while the reverse is usually trivial (e.g. it is generally much easier to take a <a href="/facts/Side_effect_(programming)/AU3GlLzG">side-effect-free</a> programming abstraction and simply add effects to it than it is to take a stateful abstraction and work around or encapsulate its propagation of state), and because of the syntactic flexibility and <a href="/facts/Referential_transparency/g0zARbAD">referential safety</a> of <a href="/facts/Hygienic_macro/Xtvz0Qhy">functional macros</a>, metalinguistic programming is mostly idiomatic of functional programming languages.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Domain-specific_language/n18H1foD">Domain-specific language</a> – Computer language specialized to a particular set of requirements or functionality</li>
<li><a href="/facts/Domain-specific_multimodeling/6HRLg9Lx">Domain-specific multimodeling</a> – Software engineering paradigm</li>
<li><a href="/facts/Language-oriented_programming/xsp4hqoy">Language-oriented programming</a> – programming paradigmPages displaying wikidata descriptions as a fallback</li>
<li><a href="/facts/Metacompiler/Ud51JPrv">Metacompiler</a> – Program that generates parsers or compilersPages displaying short descriptions of redirect targets</li>
<li><a href="/facts/Metalanguage/peNXFNUV">Metalanguage</a> – Language used to describe another language</li>
<li><a href="/facts/Metalinguistic_awareness/JLHUajU9">Metalinguistic awareness</a> – Ability to consciously reflect on the nature of language</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Structure and Interpretation of Computer Programs, Part 4 — Metalinguistic Abstraction <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Metalinguistic abstraction open-in-new

Metalinguistic abstraction