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BayHac2013/BayHac2013/Denotative Programming

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<li><em>[http://www.scribd.com/doc/12878059/The-Next-700-Programming-Languages The Next 700 Programming Languages]</em>:
 
<ul>
 
<li>By Peter Landin in 1966. Enormously important figure in improving our understanding of programming languages.
 
<ul>
 
<li>Prime move with Algol, about which Tony Hoare said “Here is a language so far ahead of its time that it was not only an improvement on its predecessors but also on nearly all its successors.”</li>
 
<li>Realized that lambda calculus can model PLs.</li>
 
<li>Worked out how to mechanically evaluate lambda calculus.</li>
 
</ul></li>
 
<li>The seminal paper on DSELs</li>
 
<li>Led to the lambda-calculus-based languages, including Scheme, ML, and Haskell.</li>
 
<li>Recommends replacing the fuzzy terms “functional”, “declarative”, and “non-procedural” with the substantive “denotative”.</li>
 
<li>“… gives us a test for whether the notation is genuinely functional or merely masquerading.”</li>
 
</ul></li>
 
<li>Denotative:
 
<ul>
 
<li>Give meaning by mapping to a mathematical type</li>
 
<li>Meaning of a composite is a function of the meanings of the components</li>
 
<li>Applies to:
 
<ul>
 
<li>Programming <em>languages</em></li>
 
<li>Programming <em>libraries</em>:
 
<ul>
 
<li>Give your data type a <em>meaning</em> (model). Examples: <code>Image</code> means function of space; <code>Animation</code> means function of time; <code>Sequence</code> means list.</li>
 
<li>Everything operation your data type must be explainable via the meaning.</li>
 
<li>Guides API, and defines correctness.</li>
 
<li>Reason on meanings, not on implementations.</li>
 
<li>For instance:
 
<ul>
 
<li>Is append on tricky-sequences associative?</li>
 
<li>Is my type a monoid, functor, applicative, etc?</li>
 
</ul></li>
 
</ul></li>
 
</ul></li>
 
<li>Strong &amp; simple (practical) foundation for (correct) reasoning</li>
 
</ul></li>
 
<li>What about Haskell?
 
<ul>
 
<li>“Purely functional”? Ill-defined question.</li>
 
<li>“Purely denotative”? If not, what parts are and what parts are not?</li>
 
</ul></li>
 
</ul>
 

Latest revision as of 02:26, 22 May 2013

oops. accidental extra indirection.