[Haskell-cafe] manage effects in a DSL

Brandon Allbery allbery.b at gmail.com
Mon Feb 10 17:16:12 UTC 2014

On Mon, Feb 10, 2014 at 11:26 AM, Dominique Devriese <
dominique.devriese at cs.kuleuven.be> wrote:

> I disagree. Just think about the Ord type class.  A decidable order
> relation for a type is definitely something I would consider a clear
> semantical meaning, but different sensible instances can be defined
> for many types...  The same thing goes for Eq or Monoid or MonadState
> or...

Sure... but now you have to make sure everything agrees about it. The way
you do this in Haskell is to give your custom instance a distinct type to
go with it. (Now go look at the Sum and Product monoids).

brandon s allbery kf8nh                               sine nomine associates
allbery.b at gmail.com                                  ballbery at sinenomine.net
unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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