Hi all,

Is there something wrong with the code below?  My anticipation was that the type of "test" would include the class constraint, because it uses the Assign constructor.  But if you load this code in GHCI you can see that the inferred type was "test :: E m -> E m".

Thanks,

  -Ryan

{-# LANGUAGE GADTs #-}

class AssignCap m 

data PureT  

data IOT  

instance AssignCap IOT 

data E m where 

  Assign  :: AssignCap m => V -> E m -> E m -> E m

  Varref  :: V -> E m

-- ...

type V = String

-- I expected the following type but am not getting it:

-- test :: AssignCap m => E m -> E m

test x = 

  case x of 

   Assign v e1 e2 -> Assign v e1 e2

-- And this is the same:

   Assign v e1 e2 -> x