[Haskell-cafe] cabal-install failure

[Duncan Coutts]

On Fri, 2008-06-13 at 11:19 -0400, Darrin Thompson wrote:
> Cabal-install is looking good. It now, for the record, has only two
> deps outside of Cabal-1.4.
> 
> I installed cabal-install-0.5 on ubuntu with the haskell.org linux
> binary for ghc 6.8.2.
> 
> I then tried cabal-install yi
> 
> Got this output:
> ... many successful installs ...
> Registering vty-3.0.1...
> Reading package info from "dist/installed-pkg-config" ... done.
> Saving old package config file... done.
> Writing new package config file... done.
> Downloading yi-0.3...
> [1 of 1] Compiling Main             ( Setup.hs, dist/setup/Main.o )
> 
> Setup.hs:9:0:
>     Warning: Deprecated use of `showPackageId'
>              (imported from Distribution.Simple, but defined in
> Distribution.Package):
>              use the Text class instead
> Linking dist/setup/setup ...
> Warning: defaultUserHooks in Setup script is deprecated.
> Configuring yi-0.3...
> Warning: Instead of 'ghc-options: -DDYNAMIC -DFRONTEND_VTY' use 'cpp-options:
> -DDYNAMIC -DFRONTEND_VTY'
> setup: alex version >=2.0.1 && <3 is required but it could not be found.
> cabal: Error: some packages failed to install:
> yi-0.3 failed during the configure step. The exception was:
> exit: ExitFailure 1
> 
> Is this a cabal problem of package problem? I would have expected it
> to fail immediately instead of discover this problem so far into
> process.

So it's failing when configuring yi because alex is not installed.

So the question is when should this get checked? I think it's not
unreasonable to have the check where it is now though perhaps we could
do better by bringing it forward.

The point is, cabal-install only checks that haskell packages are
available before beginning to install stuff. It leaves all the other
checks (build tools, C libs, custom checks in Setup.hs script etc) to be
done at the configure phase of each package.

In theory it's not impossible to imagine doing the configure phase of
every package before doing the build phase of any package but it's not
clear that it gains us that much and it's a bit more complex to do it
that way.

Duncan