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     base-prelude-1.3
Starting     colour-2.3.5
Starting     base-orphans-0.8.1
Starting     base-compat-0.11.0
Building     base-prelude-1.3
Building     colour-2.3.5
Building     base-orphans-0.8.1
Building     base-compat-0.11.0
Completed    base-orphans-0.8.1
Starting     dlist-0.8.0.7
Building     dlist-0.8.0.7
Completed    dlist-0.8.0.7
Starting     hashable-1.3.0.0
Building     hashable-1.3.0.0
Completed    base-prelude-1.3
Starting     integer-logarithms-1.0.3
Building     integer-logarithms-1.0.3
Completed    colour-2.3.5
Starting     parser-combinators-1.2.1
Building     parser-combinators-1.2.1
Completed    base-compat-0.11.0
Starting     primitive-0.7.0.0
Building     primitive-0.7.0.0
Completed    integer-logarithms-1.0.3
Starting     random-1.1
Completed    hashable-1.3.0.0
Starting     shellmet-0.0.3.0
Building     random-1.1
Building     shellmet-0.0.3.0
Failed to install shellmet-0.0.3.0
Build log ( /home/builder/.cabal/logs/ghc-8.6.3/shellmet-0.0.3.0-GxXESoPZRMR9gcwJcN8Ir9.log ):
cabal: Entering directory '/tmp/cabal-tmp-18104/shellmet-0.0.3.0'
Configuring shellmet-0.0.3.0...
Preprocessing library for shellmet-0.0.3.0..
Building library for shellmet-0.0.3.0..
[1 of 1] Compiling Shellmet
Preprocessing executable 'readme' for shellmet-0.0.3.0..
Building executable 'readme' for shellmet-0.0.3.0..
ghc: could not execute: markdown-unlit
cabal: Leaving directory '/tmp/cabal-tmp-18104/shellmet-0.0.3.0'
Starting     tagged-0.8.6
Completed    parser-combinators-1.2.1
Building     tagged-0.8.6
Completed    random-1.1
Completed    tagged-0.8.6
Completed    primitive-0.7.0.0
cabal: Error: some packages failed to install:
shellmet-0.0.3.0-GxXESoPZRMR9gcwJcN8Ir9 failed during the building phase. The
exception was:
ExitFailure 1
summoner-1.4.0.0-FXA1x3XMozqCKhc8IWDWiX depends on summoner-1.4.0.0 which
failed to install.