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| From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
| Sent: 27 June 2000 14:30
| To: [EMAIL PROTECTED]
| Subject: Method contexts
|
|
| The restriction that a method context must constrain at least one
| type variable that is quantified there has biten me:
|
|
| class Member c a | c - a where
The restriction that a method context must constrain at least one
type variable that is quantified there has biten me:
class Member c a | c - a where member :: Eq a = c - a - Bool
class Member (s a) a = Sequence s a where single :: a - s a
instance Member [a] a where member s a = elem a s
