[Haskell-cafe] Re: about Haskell code written to be "too smart"

John Lato jwlato at gmail.com
Thu Mar 26 08:36:50 EDT 2009


> From: wren ng thornton <wren at freegeek.org>
> Dan Weston wrote:
>> So to be clear with the terminology:
>>
>> inductive   = good consumer?
>> coinductive = good producer?
>>
>> So fusion should be possible (automatically? or do I need a GHC rule?) with
>>   inductive . coinductive
>>
>> Or have I bungled it?
>
> Not quite. Induction means starting from base cases and building things
> upwards from those. Coinduction is the dual and can be thought of as
> starting from the ceiling and building your way downwards (until you hit
> the base cases, or possibly forever).
>

( quite a lot of text trimmed for brevity)

Wren, thank you for contributing this post.  Coming from the point of
view of someone who doesn't grok it all yet, this is the best
commentary I've read on deforestation/fusion, and in fact is helpful
for category theory newbies as well (at least I found it so).  It
really should go on a wiki somewhere.

John Lato


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