On 09/08/07, Thomas Hartman <[EMAIL PROTECTED]> wrote: > > (sorry, forgot the subject on my first post) > > In the following code which uses template haskell, how can I get back the > macro-expanded code generated from > > $(inferStartState ''MyState) >
I just recently used ghc -ddump-splices to debug this very same problem. It turns out to be due to overlapping instances - inferStartState generates a (from memory) specific StartStateEx instance, but actually theres a general StartState => StartStateEx, and also a general Monoid=>StartState instance, and thats why the error message mentions Monoid. I guess this teaches us the reason that overlapping instances are bad: ***They don't work across modules**** Another module can add an instance which wasn't visible when a first module was compiled, and the two modules end up using different instances than expected. I've been meaning to start trying to contribute to improving the HAppS documentation, since its been such a struggle to start learning it. So the question to the HAppS people is, where is the canonical place for this documentation, where should one work? Is it the wiki page above, or the stuff inside the HAppS repository? -- [EMAIL PROTECTED] _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
