[Haskell-cafe] `seq` and categories

[Don Stewart]

jason.dusek:
>   On the IRC channel a few days ago, it was said that, as long
>   as we allow `seq`, Hask is not a valid category.
> 
>   Doesn't this basically mean that a very large amount of
>   Haskell -- anything with strictness annotations -- can not be
>   described in a category Hask?

I'm not sure of the category theoretic story, but I'd imagine so. For
background on how seq confuses reasoning (and how to restore it), see
Janis Voigtlaender's extensive, thorough work on the topic.

    http://wwwtcs.inf.tu-dresden.de/~voigt/

Also, mail:
    
    seq does not preclude parametricity
    http://www.mail-archive.com/haskell-cafe@haskell.org/msg19820.html

-- Don