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     hgmp-0.1.1
Starting     reflection-2.1.5
Starting     long-double-0.1
Building     hgmp-0.1.1
Building     long-double-0.1
Building     reflection-2.1.5
Completed    long-double-0.1
Completed    reflection-2.1.5
Completed    hgmp-0.1.1
Starting     rounded-0.2
Failed to install rounded-0.2
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/rounded-0.2-5TWe79ogI62JN34DLb51Qq.log ):
cabal: Entering directory '/tmp/cabal-tmp-19171/rounded-0.2'
Configuring rounded-0.2...
cabal: Missing dependency on a foreign library:
* Missing (or bad) C library: mpfr
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
already installed but in a non-standard location then you can use the flags
--extra-include-dirs= and --extra-lib-dirs= to specify where it is.If the
library file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.

cabal: Leaving directory '/tmp/cabal-tmp-19171/rounded-0.2'
cabal: Error: some packages failed to install:
rounded-0.2-5TWe79ogI62JN34DLb51Qq failed during the configure step. The
exception was:
ExitFailure 1