Resolving dependencies...
Downloading splay-0.0.3...
Configuring splay-0.0.3...
Building splay-0.0.3...
Failed to install splay-0.0.3
Build log ( /home/builder/.cabal/logs/splay-0.0.3.log ):
cabal: Entering directory '/tmp/cabal-tmp-18461/splay-0.0.3'
Configuring splay-0.0.3...
Building splay-0.0.3...
Preprocessing library splay-0.0.3...
[1 of 2] Compiling Data.Splay.Internal ( src/Data/Splay/Internal.hs, dist/build/Data/Splay/Internal.o )
[2 of 2] Compiling Data.Splay       ( src/Data/Splay.hs, dist/build/Data/Splay.o )

src/Data/Splay.hs:46:14: error:
    • Illegal type signature in instance declaration:
        mappend :: Measured s a => Splay s a -> Splay s a -> Splay s a
      (Use InstanceSigs to allow this)
    • In the instance declaration for ‘Monoid (Splay s a)’
cabal: Leaving directory '/tmp/cabal-tmp-18461/splay-0.0.3'
cabal: Error: some packages failed to install:
splay-0.0.3 failed during the building phase. The exception was:
ExitFailure 1