[Haskell-cafe] manage effects in a DSL

Brandon Allbery allbery.b at gmail.com
Mon Feb 10 15:03:43 UTC 2014


On Mon, Feb 10, 2014 at 5:33 AM, Dominique Devriese <
dominique.devriese at cs.kuleuven.be> wrote:

> Local instances were already considered by Wadler when he proposed
> type classes, but they are problematic to combine with type inference
>

Local instances have a bigger problem: you can use them to trivially
violate invariants. Consider a local replacement for Ord on a Data.Map.
They're not going to happen.

-- 
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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