Deprecate Foldable for Either

[Henrik Nilsson]

Hi,

Andrew Martin wrote:

 > Aside from the technical reasons, which have already been discussed
 > and decided, confused students dictating language and library design
 > has never worked out well.

Neither arguing for or against here, but let it just be clear that
it is *not* just students who have been bitten by this particular
change, but also very experienced Haskellers. And they don't like it
a bit.

Besides, is there *any* concrete evidence language and library design
necessarily must be confusing to students in order to work for real
applications?

I'd say there is plenty of evidence to the contrary. For example,
what effectively is no more than Haskell 98 is used very successfully
within Standard Chartered bank, which probably has the largest
team of Haskell programmers in the world. And they made a very 
deliberate, carefully considered choice to keep their in-house
version of Haskell simple.

Now, I am obviously not arguing to move back to Haskell 98.
But I think this example very convincingly demonstrates that
conceptual simplicity can go a very long way indeed, and that lots of
features and extensions that are seen as very important by some,
in the bigger picture perhaps were not so essential after all.
And maybe the cost imposed on the rest of the community outweighs
their benefit.

Best,

/Henrik





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