FYI, it is possible to make a "permalink" on github, which points to the code at a specific commit. Perhaps gitlab has something similar?
Alan On Tue, 28 Dec 2021 at 19:28, Richard Eisenberg <li...@richarde.dev> wrote: > We could always make a hyperlink to the source code as hosted on GitLab. > But I actually argue not to: such links would quickly become outdated, in > one of two ways: either we make a permalink, in which case the linked Note > text will become outdated; or we make a link to a particular file & line, > in which case the Note might move somewhere else. Instead, just by naming > the Note title, we have a slightly-harder-to-use link, where you use it by > grepping the source code. This is less convenient, but it will stay > up-to-date. Until we have better tooling to, say, create an HTML anchor > based on a Note, I think this is the best we can do. > > Richard > > On Dec 28, 2021, at 12:10 PM, Benjamin Redelings < > benjamin.redeli...@gmail.com> wrote: > > I was thinking about the relationship between the wiki and the notes in > the GHC source. > > Would it be possible to link directly to [compiler notes] in the GHC > source from the wiki, using hyperlinks? Right now, I'm seeing references > that look like: (See Note [Constraint flavours].) > > (I can see the motivation to include comments in the source, but I also > think that the wiki is more discoverable than the compiler source code. > So, in the interests of pursuing both approaches, it would be nice to be > able to link to notes FROM the wiki. I suppose one could include a > hyperlink to the file on github that contains the note...) > > I'm not sure how much web infrastructure would be required to make > hyperlinks for notes... > > -BenRI > On 11/8/21 5:35 AM, Simon Peyton Jones wrote: > > Is there anywhere on the GHC wiki that explains how to interpret this > output, and says that the type and dictionary applications ARE there, just > not shown by '-ddump-tc'? > > Perhaps it would be helpful to add some basic description of what comes > out of the typechecker to a page like this one? (below) > > > https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/hsc-main > <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fwikis%2Fcommentary%2Fcompiler%2Fhsc-main&data=04%7C01%7Csimonpj%40microsoft.com%7Cab59b17d2f394945ad1e08d9a2b96c81%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637719740212483767%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=WZL1VADZPUlaOACd58K1XZO5MzPOKrfLFMSuBD%2FGW44%3D&reserved=0> > Yes it would! Would you care to start such a wiki page (a new one; don’t > just clutter up the one you point to)? You can write down what you > know. Don’t worry if you aren’t 100% sure – we can correct it. And if you > outright don’t know, leave a “What should I say here?” note. > > > "This late desugaring is somewhat unusual. It is much more common to > desugar the program before typechecking, or renaming, because that presents > the renamer and typechecker with a much smaller language to deal with. > However, GHC's organisation means that > This note is now slightly out of date. We are now, very carefully, doing > some desugaring *before* typechecking. See > > - Note [Handling overloaded and rebindable constructs] in > GHC.Rename.Expr > - Note [Rebindable syntax and HsExpansion] in GHC.Hs.Expr > > > You can and should point to these and similar Notes from the wiki page you > write. Indeed there may be some part of what you write that would be > better framed as Note in GHC’s source code. > > Thanks! > > Simon > > PS: I am leaving Microsoft at the end of November 2021, at which point > simo...@microsoft.com will cease to work. Use simon.peytonjo...@gmail.com > instead. (For now, it just forwards to simo...@microsoft.com.) > > *From:* ghc-devs <ghc-devs-boun...@haskell.org> > <ghc-devs-boun...@haskell.org> *On Behalf Of *Benjamin Redelings > *Sent:* 08 November 2021 13:12 > *To:* Richard Eisenberg <li...@richarde.dev> <li...@richarde.dev> > *Cc:* ghc-devs@haskell.org > *Subject:* Re: Output language of typechecking pass? > > > Hi, > > > > Questions: > > > > 1. It seems like this separation is actually necessary, in order to apply > generalization only to let arguments written by the programmer, and not to > let bindings introduced during desugaring. Is that right? > > > > I don't think so. That is, if we did it all in one pass, I still think we > could get generalization right. > > I guess I asked this question wrong. I mean to say, if we did the two > passes in the reverse order (desugaring first, followed by typechecking), > that would not work, right? > > As the wiki says: > > "This late desugaring is somewhat unusual. It is much more common to > desugar the program before typechecking, or renaming, because that presents > the renamer and typechecker with a much smaller language to deal with. > However, GHC's organisation means that > > - error messages can display precisely the syntax that the user wrote; > and > - desugaring is not required to preserve type-inference properties. > > " > > > > 2. Does the output of type checking contain type lambdas? > > > > Yes. See below. > > > > > > 3. Does the type checking pass determine where to add dictionary arguments? > > > > Yes. See below. > > > > > > 4. Are there any other resources I should be looking at? > > > > Yes. You want to enable -fprint-typechecker-elaboration (and possible > -fprint-explicit-coercions). With the former, you get to see all this stuff > you're looking for. It's normally suppressed so that the output resembles the > user's code. > > > > I hope this helps! > > Richard > > Hmm... so, I think I see how this works now. I don't think > '-fprint-explicit-coercions' does anything here though. > > $ ghc -ddump-tc Test2.hs -fprint-typechecker-elaboration > > ... > > AbsBinds [a_a2hp] [$dNum_a2hB] > {Exports: [g <= g_a2hz > wrap: <>] > Exported types: g :: forall a. Num a => a -> a -> a > [LclId] > Binds: g x_aYk y_aYl = (y_aYl * x_aYk) + 1 > Evidence: [EvBinds{[W] $dNum_a2hs = $dNum_a2hq > [W] $dNum_a2hw = $dNum_a2hq > [W] $dNum_a2hq = $dNum_a2hB}]} > > ... > > The type and dictionary arguments are visible here (along with the > evidence bindings), but type and dictionary applications are only visible > if you use -ddump-tc-ast, which is a lot more verbose. (I don't think > there is another flag that shows these applications?) Since I didn't > initially know what "evidence" was, and there is nothing to say that a_a2hp > is a type lambda argument, this was pretty opaque until I managed to read > the tc-ast and the light went on. > > I can see now that the type and dictionary arguments are added by > annotating the AST. > > Is there anywhere on the GHC wiki that explains how to interpret this > output, and says that the type and dictionary applications ARE there, just > not shown by '-ddump-tc'? > > Perhaps it would be helpful to add some basic description of what comes > out of the typechecker to a page like this one? (below) > > > https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/hsc-main > <https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.haskell.org%2Fghc%2Fghc%2F-%2Fwikis%2Fcommentary%2Fcompiler%2Fhsc-main&data=04%7C01%7Csimonpj%40microsoft.com%7Cab59b17d2f394945ad1e08d9a2b96c81%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C637719740212483767%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=WZL1VADZPUlaOACd58K1XZO5MzPOKrfLFMSuBD%2FGW44%3D&reserved=0> > > -BenRI > > > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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