TITLE: Strange Loop 4: The Quotable Wadler
AUTHOR: Eugene Wallingford
DATE: October 01, 2018  7:12 PM
DESC: 
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BODY:

 Philip Wadler is a rockstar to the Strange Loop crowd.
 <A HREF="https://www.thestrangeloop.com/2015/propositions-as-types.html">
    His 2015 talk</A>
 on propositions as types introduced not a few developers to one of
 computer science's great unities.  This year, he returned to add a
 third idea to what is really a triumvirate: categories.  With a
 little help from his audience, he showed that category theory has
 elements which correspond directly to ...
 <UL>
 <LI> logical 'and', which models the record (or tuple, or pair) data
      type </LI>
 <LI> logical 'or', which models the union (or variant record) data
      type </LI>
 <LI> a map, which models the function data type </LI>
 </UL>
 What's more, the product/sum dual models
 <A HREF="https://en.wikipedia.org/wiki/De_Morgan%27s_laws">
    De Morgan's laws</A>,
 but with more structure, which enables it to model sets beyond the
 booleans!

 Wadler is an entertaining teacher; I recommend the video of his talk!
 But he is also as quotable as any CS prof I've encountered in a long
 while.  Here is a smattering of his great lines from "Categories for
 the Working Hacker":

 <BLOCKQUOTE><EM>
 If you can use math to do something, do it.  It will make your life
 better.
 </EM></BLOCKQUOTE>

 <BLOCKQUOTE><EM>
 That's the great thing about math.  It lets you see something obvious
 after only thirty or forty years.
 </EM></BLOCKQUOTE>

 <BLOCKQUOTE><EM>
 Pick your favorite algebra.  If you don't have one, get one.
 </EM></BLOCKQUOTE>

 <BLOCKQUOTE><EM>
 Let's do that in Java.  That's what you should always do when you
 learn a new idea: do it in Java.
 </EM></BLOCKQUOTE>

 <BLOCKQUOTE><EM>
 That's what category theory is really about: avoiding traffic jams.
 </EM></BLOCKQUOTE>

 <BLOCKQUOTE><EM>
 Sums are the secret origin of folds.
 </EM></BLOCKQUOTE>

 <BLOCKQUOTE><EM>
 If you don't understand this, I don't mind, because it's Java.
 </EM></BLOCKQUOTE>

 While watching the presentation, I created a one-liner of my own:
 <EM>Surprise!  If you do something that matches exactly what Haskell
 does, Haskell code will be much shorter than Java code</EM>.

 This was a very good talk; I enjoyed it quite a bit.  However, I
 also left the room with a couple of nagging questions.  The talk
 was titled "Categories for the Working Hacker", and it did a nice
 job of presenting some basic ideas from category theory in a way
 that most any developer could understand, even one without much
 background in math.  But...  How does this knowledge make one a
 better hacker?  Armed with this new, entertaining knowledge, what
 are software developers able to do that they couldn't do before?

 I have my own ideas for answers to these questions, but I would
 love to hear Wadler's take.
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