Hide fields from deriving (Show)

Question

Imagine I have a data record with many fields:

data DataRecord = DataRecord {
    field1 :: String,
    field2 :: String,
    ...
} deriving (Show)

Is it possible to hide some fields from the deriving (Show) or do have to implement my own show function for DataRecord?

Reason for my question: When I have cyclic dependencies between two data records both using deriving (Show) the show function would generate an infinite string.

Answer 1

The Haskell 2010 report mentions your cyclic dependencies as unsuitable case:

The derived Read and Show instances may be unsuitable for some uses. Some problems include:

• Circular structures cannot be printed or read by these instances.

So you need to specify the instance by hand.