Whoops, I replied via email instead of commenting on the ticket. I've done so now. Sorry for the mailing list noise.
On Mon, Jun 11, 2018, 08:21 Nicolas Frisby <nicolas.fri...@gmail.com> wrote: > That way of saying it clarifies the expectations for me. And doesn't seem > too burdensome for the plugin author. > > Thus I think this ticket could be resolved by updating the documentation. > (Though I still would like for a plugin to be able to request the flattened > Wanteds. Separate ticket?) > > In particular this sentence in the User Guide > > "[The plugin] will be invoked at two points in the constraint solving > process: after simplification of given constraints, and after unflattening > of wanted constraints." > > would benefit from some elaboration. Specifically, "unflattening of wanted > constraints" is somewhat ambiguous: until you spelled it out, I was > thinking that if a constraint is flattened, it doesn't have any flattening > variables in it. However, I'm inferring here that the jargon is used to > mean that "unflattening a wanted constraint" only eliminates fmvs, possibly > leaving fsks behind? That's what I've been confused about (until now, I > think). Thanks. > > > On Tue, Jun 5, 2018, 01:48 GHC <ghc-devs@haskell.org> wrote: > >> #15147: Type checker plugin receives Wanteds that are not completely >> unflattened >> >> -------------------------------------+------------------------------------- >> Reporter: nfrisby | Owner: (none) >> Type: bug | Status: new >> Priority: normal | Milestone: 8.6.1 >> Component: Compiler (Type | Version: 8.4.1 >> checker) | Keywords: >> Resolution: | TypeCheckerPlugins >> Operating System: Unknown/Multiple | Architecture: >> | Unknown/Multiple >> Type of failure: None/Unknown | Test Case: >> Blocked By: | Blocking: >> Related Tickets: | Differential Rev(s): >> Wiki Page: | >> >> -------------------------------------+------------------------------------- >> >> Comment (by simonpj): >> >> > Perhaps I'm misunderstanding something >> >> I didn't express it very clearly. As it stands, the Given CFunEqCan's >> remain, and hence so do the fsks. The Wanted CFunEqCans are removed >> (currently) along with the fmvs. >> >> So yes, currently Wanteds can contain fsks, whose definition is given by >> a >> CFunEqCan. I would have thought that most plugins would not find it hard >> to deal with that. >> >> -- >> Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15147#comment:14> >> GHC <http://www.haskell.org/ghc/> >> The Glasgow Haskell Compiler >> >
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