-ddump-types vs -fprint-explicit-foralls, and symbol-ness of worker/wrapper names [Re: [commit: ghc] master: Pretty-print the following TyThings via their IfaceDecl counterpart: * AnId * ACoAxiom * AConLike (065c35a) (fwd)]

Johan Tibell johan.tibell at gmail.com
Mon Mar 17 14:00:04 UTC 2014

On Mon, Mar 17, 2014 at 2:45 PM, Simon Peyton Jones
<simonpj at microsoft.com>wrote:

> | The one interesting case is T4306 which fails because the generated name
> | $wupd is regarded as an infix name, and thus with my new code is
> | rendered as
> |
> |    ($wupd) :: GHC.Prim.Double# -> GHC.Prim.Double#
> |
> | instead of the old
> |
> |    $wupd :: GHC.Prim.Double# -> GHC.Prim.Double#
> I think it'd also be ok just to accept this output too. These "$wxx" names
> are generated by GHC and won't show up in user output.  It doesn't much
> matter displaying them in parens.

Do they show up in -ddump-simpl? It would be nice to keep that output as
readable as possible, as there are quite a few of us that read it on a
regular basis.

> But changing isLexVarSym is probably equally fine too.  I think (worth a
> check) that it's only called for display purposes, and not in any
> performance-critical parts.
> Whichever you choose, add a Note with isLexVarSym to explain the issue and
> the choice.

Does that mean that any operator that starts with $ will now not be
considered infix for printing purposes?

-- Johan
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