Ah -- so use cabal-dev for development and cabal-install when a version stabilizes? -- Conal
On Sun, Feb 5, 2012 at 4:20 PM, Jason Dagit <dag...@gmail.com> wrote: > On Sun, Feb 5, 2012 at 10:48 AM, Conal Elliott <co...@conal.net> wrote: > > On Sun, Feb 5, 2012 at 12:43 AM, Andres Löh <andres.l...@googlemail.com> > > wrote: > >> > >> Hi Conal. > >> > >> > Thanks for the reply! Note that I get this message even running 'cabal > >> > install' a second time after changing nothing. Is that scenario an > >> > example > >> > of what you mean by a "potentially dangerous cabal invocation"? > >> > >> The check currently is entirely ad-hoc. Any reinstallation of an > >> existing package triggers the warning. There's no hash comparison. > > > > > > I'm confused. Isn't package re-installation an extremely common thing in > > cabal while developing software? > > I would say, "You should never mutate your user or global package > database" and recommend using cabal-dev. The way cabal-install does > destructive updates is evil. In particular, it likes to mutate your > global or user package database. You run the risk of building > something and then breaking it later by mutating its dependencies. > > With cabal-dev it would be more like this: > # Suppose you're in the source of bar > # Further suppose you just changed > # dependency 'foo' that you're also developing > cabal-dev add-source ../foo > cabal-dev install --reinstall foo > > Technically this still mutates a package database but, it's a > throwaway package database in the bar directory. I lose very little > when I 'rm -rf cabal-dev dist' and my user and global package > databases stay in tact. I feel as though I can't sing the > sandboxed-build praise loudly enough. The time my computer takes to > rebuild packages is negligible to the human time spent dealing with > broken package databases.. > > I hope that helps, > Jason >
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