{"id":252863,"date":"2009-07-01T02:06:48","date_gmt":"2009-07-01T09:06:48","guid":{"rendered":"https:\/\/www.microsoft.com\/en-us\/research\/?post_type=msr-research-item&#038;p=252863"},"modified":"2018-10-16T20:08:36","modified_gmt":"2018-10-17T03:08:36","slug":"classes-jim-not-know-2009","status":"publish","type":"msr-research-item","link":"https:\/\/www.microsoft.com\/en-us\/research\/publication\/classes-jim-not-know-2009\/","title":{"rendered":"Classes, Jim, but not as we know them (2009)"},"content":{"rendered":"<p>Haskell is now quite widely used, but its most important contributions are the <em>ideas<\/em> that it embodies. In this talk I will focus on one of these ideas, namely type classes, with a few anecdotes and reflections along the way about the <a href=\"https:\/\/www.microsoft.com\/en-us\/research\/publication\/a-history-of-haskell-being-lazy-with-class\/\">process of developing the language<\/a>.<\/p>\n<p>Type classes are probably Haskell&#8217;s most distinctive feature. The original idea is very neat and, better still, it led to a long series of subsequent generalisations and innovations. Indeed, although the language is now nineteen years old, Haskell&#8217;s type system is still in a state of furious development. For example, I am involved in adding type-level functions to Haskell, as I will briefly describe.<\/p>\n<p>I will explain what type classes are, how they differ from the classes of mainstream object oriented languages, why I think they are so cool, and what the hot topics are. I&#8217;ll give plenty of examples, so you don&#8217;t need to already know Haskell.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Haskell is now quite widely used, but its most important contributions are the ideas that it embodies. In this talk I will focus on one of these ideas, namely type classes, with a few anecdotes and reflections along the way about the process of developing the language. Type classes are probably Haskell&#8217;s most distinctive feature. 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