Sorry, I sent the email to the wrong place and messed up the code (it's early :)). Take two: transform = everywhere (mkT transform') where transform = (\Term a->Flattened a) `extT` (Contstant a->Flattened a) On 12/19/06, Vyacheslav Akhmechet wrote:

That should be pretty simple. This code probably won't work, but you can use it as an example to look into this further.

transform everywhere = (mkT transform') where transform = (\Term a->Flattened a) `extT` (Contstant a->Flattened a)

Something like this should work. Look into the docs for more info.

On 12/19/06, Grote Collective wrote:

...

Hello all,

I have two datatypes, both representing the same language. However, one is a "flattened" version of the other. For instance:

data Flattened = Const Flattened | Sum Flattened Flattened | ... | IntConst Int | RealConst Float | BoolConst Bool | Void

----

data Term = Const Constant | Sum Term Term | ...

data Constant = IntConst Int | RealConst Float | BoolConst Bool | Void

Now I want to create functions to convert between these two datatypes. This is easy to do but *very* tedious in its most naive approach. However, I think I can use Data.Generics to make a simple implementation of both functions. The question is: can I? I think that this conversion is a simple fold over the structure, changing merely the constructor name (the qualified name, because the unqualified name is the same), but I cannot seem to understand from the documentation how to do this...

Thanks in advance, Mark Smith

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