Opal (programming language)

<h2 id="example-program">Example program</h2>
<p>This is an example OPAL program, which calculates the <a href="/facts/Greatest_Common_Divisor/kNFvBuKl">GCD</a> recursively.
</p>
Signature file (declaration)
   SIGNATURE GCD
   FUN GCD: nat ** nat -> nat

Implementation file (definition)
   IMPLEMENTATION GCD
   IMPORT Nat COMPLETELY
   DEF GCD(a,b) == IF a % b = 0 THEN b
                       ELSE IF a-b < b THEN GCD(b,a-b)
                           ELSE GCD(a-b,b)
                       FI
                   FI

<h2 id="external-links">External links</h2>
<ul><li><a href="https://web.archive.org/web/20170823091221/http://projects.uebb.tu-berlin.de/opal/trac">The OPAL Home Page</a>, archived, last modified 30 September 2010.</li>
<li><a href="https://web.archive.org/web/20120426022221/http://projects.uebb.tu-berlin.de/opal/trac/wiki/InstallationEnglish">OPAL Installation Guide</a>, archived.</li></ul>

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

<ol>
<li id="fn:1"><p>"Opal". TU-Berlin/opal - Optimized Applicative Language. Retrieved 2023-09-23. <a href="https://github.com/TU-Berlin/opal" target="_blank">https://github.com/TU-Berlin/opal</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"Home page". OPAL Project. Retrieved 2023-11-25. <a href="https://www.opal-project.de/" target="_blank">https://www.opal-project.de/</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
</ol>

Opal (programming language) open-in-new

Opal (programming language)