Resolving dependencies...
Configuring dataenc-0.12...
Configuring mtl-2.2.1...
Building mtl-2.2.1...
Building dataenc-0.12...
Installed dataenc-0.12
Configuring old-locale-1.0.0.7...
Building old-locale-1.0.0.7...
Configuring text-1.2.2.1...
Installed mtl-2.2.1
Building text-1.2.2.1...
Installed old-locale-1.0.0.7
Installed text-1.2.2.1
Configuring parsec-3.1.11...
Building parsec-3.1.11...
Installed parsec-3.1.11
Configuring buster-2.21...
Building buster-2.21...
Failed to install buster-2.21
Build log ( /home/builder/.cabal/logs/buster-2.21.log ):
cabal: Entering directory '/tmp/cabal-tmp-11893/buster-2.21'
Configuring buster-2.21...
Warning: The 'license-file' field refers to the file '' which does not exist.
Building buster-2.21...
Preprocessing library buster-2.21...
[1 of 6] Compiling App.EventBus     ( App/EventBus.hs, dist/build/App/EventBus.o )

App/EventBus.hs:224:10: error:
    • Illegal instance declaration for ‘Monoid (Behaviour a)’
        (All instance types must be of the form (T a1 ... an)
         where a1 ... an are *distinct type variables*,
         and each type variable appears at most once in the instance head.
         Use FlexibleInstances if you want to disable this.)
    • In the instance declaration for ‘Monoid (Behaviour a)’
cabal: Leaving directory '/tmp/cabal-tmp-11893/buster-2.21'
cabal: Error: some packages failed to install:
buster-2.21 failed during the building phase. The exception was:
ExitFailure 1