This seems like a silly question, but how can we install cabal-install
now? The latest hackage version 220.127.116.11 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
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.
> Wolfgang Jeltsch <[hidden email]> 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.
> - Ben
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