seeking ideas for short lecture on type classes

[Fergus Henderson]

On 26-Jan-2003, Norman Ramsey <nr@eecs.harvard.edu> wrote:
>  > > In a fit of madness, I have agreed to deliver a 50-minute lecture
>  > > on type classes to an audience of undergraduate students.  These
>  > > students will have seen some simple typing rules for F2 and will
>  > > have some exposure to Hindley-Milner type inference in the context
>  > > of ML.
>  > 
>  > Will they have had exposure to more "traditional" OO programming?  If
>  > so, it might be useful to note the difference between Haskell type
>  > classes and C++/Java/whatever classes, namely that Haskell decouples
>  > types and the interfaces that they support.  The advantage is that you
>  > can extend a type with a new interface at any point, not just when you
>  > define the type.
> 
> Hmm --- you are talking about the `instance' declarations, right?

Yes -- the fact that Haskell has separate instance declarations,
as opposed to making this information part of the `data' declaration.
In most OO languages inheritence relations need to be specified in the
type definition.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.