[Haskell-cafe] adding the elements of two lists

Jerzy Karczmarczuk jerzy.karczmarczuk at unicaen.fr
Sun Mar 25 14:41:52 CEST 2012

TP  :
> However, it seems it is not possible to do that:
> -------------------
> instance Num [Int] where
> 	l1 + l2 = ....
> -------------------
> Why?
Why not?? It is possible.

All what has been said by other people is right.
But you can do it your way as well, GHC won't protest if you :set 
-XFlexibleInstances .

(Then you might have some other "small" problems, but nobody is perfect).

Jerzy Karczmarczuk

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