[Haskell-cafe] Curious why "cabal upgrade parsec" not installing latest version

Ivan Lazar Miljenovic ivan.miljenovic at gmail.com
Wed Sep 15 23:00:39 EDT 2010

On 16 September 2010 12:47, Peter Schmitz <ps.haskell at gmail.com> wrote:
> Not that I'm having any problem with parsec, but I guess I
> would like to install the latest (3.1.0), unless there is a reason
> not to.

Because Parsec-3 apparently still has some speed regressions compared
to Parsec-2 (I'm not qualified to note whether its design is slow or
if you have to use it differently to get good performance out of it),
so many developers prefer to stick to Parsec-2 for this reason.

As such, and because a lot of Cabal files just state "parsec" without
a dependency, by default cabal-install will assume that an unversioned
dependency (which includes installing/upgrading it via the command
line) refers to Parsec-2 and not Parsec-3.

Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com

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