Am Donnerstag, den 03.12.2009, 01:40 +0100 schrieb Sjoerd Visscher:
The idea is that there's just enough unwrapping such that you don't need to use getDual and appEndo.
Yes, but what does Dual [1] `mappend Dual [2] mean then? Should it use the Monoid instance of Dual and return Dual [2, 1] ? Should it unwrap the lists beforehand and re-wrap them afterwards and return Dual [1, 2] ? Should it unwrap the resulting list afterwards and return [1, 2] or even [2,1] ? That's not obvious to me.
On Dec 3, 2009, at 1:25 AM, Holger Siegel wrote:
Am Donnerstag, den 03.12.2009, 01:16 +0100 schrieb Martijn van Steenbergen:
So here's a totally wild idea Sjoerd and I came up with.
What if newtypes were unwrapped implicitly?
What advantages and disadvantages would it have? In what cases would this lead to ambiguous code?
1) instance Monoid a => Monoid (Dual a)
2) instance Monoid (Endo a) instance Monoid b => Monoid (a -> b)
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-- Sjoerd Visscher sjoerd@w3future.com