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.

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Resolving dependencies...
Starting     primitive-0.6.4.0
Building     primitive-0.6.4.0
Completed    primitive-0.6.4.0
Downloading  posix-api-0.1.0.0
Downloaded   posix-api-0.1.0.0
Starting     posix-api-0.1.0.0
Building     posix-api-0.1.0.0
Failed to install posix-api-0.1.0.0
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/posix-api-0.1.0.0-275krMPZxPr8oUfOjYuh6e.log ):
cabal: Entering directory '/tmp/cabal-tmp-10039/posix-api-0.1.0.0'
Configuring posix-api-0.1.0.0...
Preprocessing library for posix-api-0.1.0.0..
Building library for posix-api-0.1.0.0..
[1 of 6] Compiling Posix.Directory  ( src/Posix/Directory.hs, dist/build/Posix/Directory.o )
[2 of 6] Compiling Posix.Socket.Types ( dist/build/Posix/Socket/Types.hs, dist/build/Posix/Socket/Types.o )

src/Posix/Socket/Types.hsc:170:15: error: parse error on input ‘{’
    |
170 | peek = Flags #{const MSG_PEEK}
    |               ^
cabal: Leaving directory '/tmp/cabal-tmp-10039/posix-api-0.1.0.0'
cabal: Error: some packages failed to install:
posix-api-0.1.0.0-275krMPZxPr8oUfOjYuh6e failed during the building phase. The
exception was:
ExitFailure 1