Resolving dependencies...
Downloading fst-0.9...
Warning: fst.cabal: Unknown fields: build-depends (line 15)
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
Warning: fst.cabal: Unknown fields: executable (line 32)
Fields allowed in this section:
main-is, buildable, build-tools, build-depends, cpp-options,
cc-options, ld-options, pkgconfig-depends, frameworks, c-sources,
js-sources, default-language, other-languages, default-extensions,
other-extensions, extensions, extra-libraries,
extra-ghci-libraries, extra-lib-dirs, includes, install-includes,
include-dirs, hs-source-dirs, other-modules, ghc-prof-options,
ghcjs-prof-options, ghc-shared-options, ghcjs-shared-options,
ghc-options, ghcjs-options, jhc-options, hugs-options,
nhc98-options
Configuring fst-0.9...
Building fst-0.9...
Preprocessing library fst-0.9...

FST/Alex.hs:1:1:
    Ambiguous module name ‘Prelude’:
      it was found in multiple packages: base haskell98-2.0.0.3
Failed to install fst-0.9
cabal: Error: some packages failed to install:
fst-0.9 failed during the building phase. The exception was:
ExitFailure 1