[Haskell-cafe] About instance

[Ulises Juarez Martinez]

Hi.

I have the next definitions:

type Ocurrence = (String, Int)
type Inside = [Ocurrence]

data Pattern = Return Inside
  | Abort
  | Filter (Ocurrence -> Bool) Pattern

beyond :: Pattern -> Pattern
beyond (Filter pred Abort) = Abort
-- more definitions of beyond

optimous :: Pattern -> Pattern
optimous p = fixPoint beyond p
	where fixPoint f x = if(f x == x) then x else fixPoint f (f x)

When I load the program an error is produced:

ERROR - An instance of Eq (Event -> Bool) is required to derive Eq Pattern

I put:

data Pattern = Return Inside
  | Abort
  | Filter (Ocurrence -> Bool) Pattern
  deriving (Eq)

and a new error was produced:

ERROR - An instance of Eq (Ocurrence -> Bool) is required to derive Eq 
Pattern

Who can I do an instance of Eq (Ocurrence -> Bool)? Is there another option 
to avoid the error?

Regards
Ulises

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