Resolving dependencies...
Downloading 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:45:26:
    Not in scope: type constructor or class ‘Monoid’
    Perhaps you meant ‘Monad’ (imported from Prelude)
Failed to install 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