Let we have data in one module as this:
data Person = Person { personId :: Int, name :: String }
data Address a = Address { personId :: Int, address :: String , way ::
a}
It was discussed a lot in topics "OverloadedRecordFields"
This is an alternative:
Let we have polymorphic typeclass:
class Record{f} a b | a -> b where
f :: a -> b
so, compiler could create instances for our data as:
instance Record{personId} Person Int where
personId (Person x _) = x
instance Record{personId} (Address a) Int where
personId (Address x _ _) = x
instance Record{way} (Address Int) Int where
way (Address _ _ x) = x
and we could use this:
p:: Record {personId} r Int => r -> Int
p = personId
What do you think about this?
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