Thanks to those who responded to this thread about 'deriving'. My current thoughts are: * I'd be happy to add the ability to separate a 'deriving' clause from its data type declaration, if we can agree syntax (see below). It's fairly easy to do; it makes the language more orthogonal; it's useful. But in fact I think only Martin Sjögren has explicitly said that the feature would be useful.... and every feature has a cost. * I'm not at all keen on making '..deriving( Foo )' mean $(derive 'Foo) or something like that. Just make the TH call yourself! * No one is arguing hard for instance declarations in hi-boot files, so let's leave that for now. Re syntax, the obvious possibility (A) is to add derive( pred1, .., predn ) as a new top-level declaration. E.g. derive( Typeable (T a) ) But that means adding 'derive' as a keyword. Other possibilities: deriving( Typeable (T a) ) -- (B) Re-use 'deriving' keyword The trouble with (B) is that the thing inside the parens is different in this situation than in a data type declaration. Any other ideas? Simon