Warning: The install command is a part of the legacy v1 style of cabal usage.

Please switch to using either the new project style and the new-install
command or the legacy v1-install alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

For more information, see: https://wiki.haskell.org/Cabal/NewBuild

Resolving dependencies...
Starting     mmsyn3-0.1.4.0
Starting     mmsyn5-0.4.3.0
Starting     primitive-0.7.0.1
Building     mmsyn3-0.1.4.0
Building     primitive-0.7.0.1
Building     mmsyn5-0.4.3.0
Completed    mmsyn5-0.4.3.0
Completed    mmsyn3-0.1.4.0
Completed    primitive-0.7.0.1
Starting     vector-0.12.1.2
Building     vector-0.12.1.2
Completed    vector-0.12.1.2
Starting     mmsyn2-0.1.7.0
Building     mmsyn2-0.1.7.0
Completed    mmsyn2-0.1.7.0
Starting     mmsyn6ukr-0.6.3.1
Building     mmsyn6ukr-0.6.3.1
Completed    mmsyn6ukr-0.6.3.1
Starting     mmsyn7s-0.6.6.0
Starting     mmsyn7ukr-0.15.3.0
Building     mmsyn7ukr-0.15.3.0
Building     mmsyn7s-0.6.6.0
Completed    mmsyn7s-0.6.6.0
Completed    mmsyn7ukr-0.15.3.0
Starting     mmsyn7h-0.7.3.1
Building     mmsyn7h-0.7.3.1
Failed to install mmsyn7h-0.7.3.1
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/mmsyn7h-0.7.3.1-ETMKRPsiu5Z3DJJr5YT9fG.log ):
cabal: Entering directory '/tmp/cabal-tmp-3620/mmsyn7h-0.7.3.1'
Configuring mmsyn7h-0.7.3.1...
Preprocessing executable 'mmsyn7h' for mmsyn7h-0.7.3.1..
Building executable 'mmsyn7h' for mmsyn7h-0.7.3.1..

<no location info>: warning: [-Wmissing-home-modules]
    These modules are needed for compilation but not listed in your .cabal file's other-modules: 
        MMSyn7h
[1 of 2] Compiling MMSyn7h          ( MMSyn7h.hs, dist/build/mmsyn7h/mmsyn7h-tmp/MMSyn7h.o )

MMSyn7h.hs:139:39: error:
    parse error on input ‘<-’
    Perhaps this statement should be within a 'do' block?
    |
139 |                                then _ <- readProcessWithExitCode (fromJust . showE $ "play") [nameSF ++ snd ws] "" >> return ()
    |                                       ^^
cabal: Leaving directory '/tmp/cabal-tmp-3620/mmsyn7h-0.7.3.1'
cabal: Error: some packages failed to install:
mmsyn7h-0.7.3.1-ETMKRPsiu5Z3DJJr5YT9fG failed during the building phase. The
exception was:
ExitFailure 1