Resolving dependencies...
Downloading bla-2009.10.20...
Warning: bla.cabal: Unknown fields: build-depends (line 13)
Fields allowed in this section:
name, version, cabal-version, build-type, license, license-file,
license-files, copyright, maintainer, stability, homepage,
package-url, bug-reports, synopsis, description, category, author,
tested-with, data-files, data-dir, extra-source-files,
extra-tmp-files, extra-doc-files
Configuring bla-2009.10.20...
Building bla-2009.10.20...
Preprocessing executable 'bla' for bla-2009.10.20...

src/bla.hs:1:8:
    Ambiguous module name ‘Prelude’:
      it was found in multiple packages: base haskell98-2.0.0.3
Failed to install bla-2009.10.20
cabal: Error: some packages failed to install:
bla-2009.10.20 failed during the building phase. The exception was:
ExitFailure 1