[Haskell-cafe] Monad laws in presence of bottoms

Sebastian Fischer fischer at nii.ac.jp
Tue Feb 21 00:28:13 CET 2012

On Mon, Feb 20, 2012 at 7:42 PM, Roman Cheplyaka <roma at ro-che.info> wrote:

> Is there any other interpretation in which the Reader monad obeys the
> laws?

If "selective strictness" (the  seq  combinator) would exclude function
types, the difference between  undefined  and  \_ -> undefined  could not
be observed. This reminds me of the different language levels used by the
free theorem generator [1] and the discussions whether  seq  should have a
type-class constraint..


[1]: http://www-ps.iai.uni-bonn.de/cgi-bin/free-theorems-webui.cgi
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