On 04 April 2006 14:35, Bulat Ziganshin wrote:

Hello Ross,

Tuesday, April 4, 2006, 4:55:09 PM, you wrote:

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http://www.cse.unsw.edu.au/~dons/haskell-1990-2000/msg00727.html (Making 'deriving' a separate declaration instead of a clause)

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Orphan instances are discouraged in the GHC libraries, so there might not be much support for adding a feature designed to permit orphan derived instances.

sorry, i don't understand how them are discouraged? GHC can't support this because of it's internal limits? i think you mean some other thing but i can't understand you

Discouraged in the sense of "it works fine, but we don't recommend it". Compilation times may be worse if you have orphan instances, because the compiler *always* has to read an interface file containing an orphan instance if it is in the transitive closure of imported modules. Cheers, Simon