Simplification of instances

David Waern david.waern at
Fri Sep 28 19:35:48 CEST 2012

2012/9/28 Simon Peyton-Jones <simonpj at>:
> Ahem.  DFuns (what you get from is_dfun of a ClsInst) now have some "silent" arguments, that are added by GHC and are not part of the original instance declaration. See
> Note [Silent superclass arguments] in TcInstDcls.
> But you don't want to print them.  Just do what InstEnv.pprInstanceHdr does (in InstEnv) to drop the silent arguments.
> I've added some more comments (commit to come).


I've written a Haddock patch that drops the arguments.


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