It seems like you would, going by semantics of System F, where types with type variables name a certain subset of types, => constraints further restrict the types of the same "shape" (are they an independent kind of restriction?), so typeclass declarations with/without => specify a partial order over types because the subset relation is. On Mon, Nov 14, 2011 at 3:47 AM, Patrick Browne <patrick.browne@dit.ie> wrote:

Is there a partial order on Haskell type classes? If so, does it induce any quasi-order relation on types named in the instances? In the example below types C and D have the same operation f Thanks, Pat

data C = C deriving Show data D = D deriving Show

class A t where  f::t->t  f t = t

instance A C where instance A D where

class A t => B t where

instance B C where instance B D where

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