[Haskell-cafe] Need help: Cabal rejecting stringsearch, conflict in base

I don't know what to do. :-( I can't install scotty or yesod. $ cabal install scotty cabal: Could not resolve dependencies: trying: scotty-0.5.0 (user goal) trying: base-4.7.0.0/installed-dc1... (dependency of scotty-0.5.0) trying: wai-extra-1.3.4.6 (dependency of scotty-0.5.0) trying: stringsearch-0.3.6.4 (dependency of wai-extra-1.3.4.6) rejecting: stringsearch-0.3.6.4:-base3 (conflict: base==4.7.0.0/installed-dc1..., stringsearch-0.3.6.4:base3 => base>=2 && <3) rejecting: stringsearch-0.3.6.4:+base3 (conflict: base==4.7.0.0/installed-dc1..., stringsearch-0.3.6.4:base3 => base>=3 && <4) Backjump limit reached (change with --max-backjumps).