Thanks for the reply. I got cabal-install from https://github.com/haskell/cabal/ and assumed it was the latest version... but now that I look carefully I see it has a 2.0 branch. I compiled it and I don't get that confusing "parse error" any more. It looks like a nicer error message in general too (except still missing some spaces, specifically "After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: karya, ekgTrying configure anyway."), so that's probably thanks to the solver improvements in 2.0.
Since it's apparently just a bug in older cabal-installs I guess I won't bother trying to find it. On Wed, Jul 26, 2017 at 7:01 PM, Wolfgang Jeltsch <wolfgang...@jeltsch.info> wrote: > Hi! > > I ran into the same problem. > > Apparently, we need cabal-install 2.0, which has not been released yet. > A preliminary solution is to use the development version from the 2.0 > branch. Binary packages can be found at > > http://ppa.launchpad.net/hvr/ghc/ubuntu/pool/main/c/cabal-install-2.0/ , > > for example. It is possible to extract the cabal-install executable from > these packages, so that it can be installed without using some Linux > distribution package manager. > > All the best, > Wolfgang > > Am Mittwoch, den 26.07.2017, 18:45 -0700 schrieb Evan Laforge: >> This seems like a silly question, but how can we install cabal-install >> now? The latest hackage version 1.24.0.2 has Cabal (>=1.24.2 && >> <1.25), but it looks like ghc Cabal is now at 2.*. >> >> I ran into this because if I get: >> >> % cabal install --only-dependencies >> Resolving dependencies... >> cabal: internal error when reading package index: failed to parse >> .cabal >> fileThe package index or index cache is probably corrupt. Running >> cabal update >> might fix it. >> >> It seems to be triggered by having 'ekg' in the deps list, since if I >> take it out then I get some other errors about packages not liking the >> new base, which is true. 'ekg' also doesn't like the new base, but >> "internal error" is not the clearest way to express that :) >> >> It's frustrating that cabal-install still doesn't report the parse >> error, even though the parse function returns one. It just ignores >> the ParseFailed case. I was going to try fixing it and send a pull >> request when I ran into the Cabal 2.* problem. >> >> On Wed, Jul 26, 2017 at 7:15 AM, Ben Gamari <b...@smart-cactus.org> >> wrote: >> > >> > Wolfgang Jeltsch <wolfgang...@jeltsch.info> writes: >> > >> > > >> > > Am Samstag, den 22.07.2017, 23:03 -0400 schrieb Ben Gamari: >> > > > >> > > > In addition, there are a number of new features, >> > > > >> > > > * A new, more type-safe type reflection mechanism >> > > > >> > > > * The long-awaited Backpack module system >> > > > >> > > > * Deriving strategies to disambiguate between GHC's various >> > > > instance >> > > > deriving mechanisms >> > > > >> > > > * Unboxed sum types, for efficient unpacked representation of >> > > > sum >> > > > data types >> > > > >> > > > * Compact regions, allowing better control over garbage >> > > > collection >> > > > in the presence of large heaps containing many long-lived >> > > > objects. >> > > > >> > > > * Colorful messages and caret diagnostics for more legible >> > > > errors >> > > > >> > > > A more thorough list of the changes in this release can be found >> > > > in >> > > > the release notes, >> > > > >> > > > https://haskell.org/ghc/docs/8.2.1/docs/html/users_guide/8.2.1 >> > > > -notes.html >> > > It seems that the release notes mention the new type reflection >> > > mechanism und colorful messages only in the “Highlights” section, >> > > not in >> > > the “Full details” section, and that they do not mention the >> > > Backpack >> > > module system and unboxed sums at all. >> > > >> > Yes, indeed these were oversights. They are fixed in the ghc-8.2 >> > branch >> > and I will try to push newly generated documentation shortly. >> > >> > Cheers, >> > >> > - Ben >> > >> > _______________________________________________ >> > Glasgow-haskell-users mailing list >> > Glasgow-haskell-users@haskell.org >> > http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-use >> > rs >> > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-users
