nikpkgs build currently broken

[wbadart]

Hey team-

I know this isn't strictly an hpython issue (probably more of a nixpkgs problem) but I wanted to post here to let you know I'm working on a fix and to solicit help from anyone with a bit of nix experience (I'm a proper nix n00b).

I'm not super familiar with how nixpkgs generates the haskellPackages set, but it seems to be a somewhat mechanical process based on what's out there on Hackage. It looks like some part of the dependency specification that works for Travis here but not for this Hackage to haskellPackages process, and I'm looking in to what that could be.

Output of nix-build '<nixpkgs>' -A haskellPackages.hpython

these derivations will be built:
  /nix/store/64j47mjb87ynnlrb7wghxqydxap80n6k-hpython-0.3.drv
building '/nix/store/64j47mjb87ynnlrb7wghxqydxap80n6k-hpython-0.3.drv'...
setupCompilerEnvironmentPhase
Build with /nix/store/kad2r4i74bcrwi53sdbh3mf85n7qbcaf-ghc-8.8.3.
unpacking sources
unpacking source archive /nix/store/vi68lra5qkwdv02svrf9676kafsryy4l-hpython-0.3.tar.gz
source root is hpython-0.3
setting SOURCE_DATE_EPOCH to timestamp 1000000000 of file hpython-0.3/test/files/weird2.py
patching sources
compileBuildDriverPhase
setupCompileFlags: -package-db=/private/tmp/nix-build-hpython-0.3.drv-0/setup-package.conf.d -j4 -threaded -rtsopts
[1 of 1] Compiling Main             ( Setup.hs, /private/tmp/nix-build-hpython-0.3.drv-0/Main.o )
Linking Setup ...
configuring
configureFlags: --verbose --prefix=/nix/store/mia0z4sx6nllm8sna75kd21jhnks0q7h-hpython-0.3 --libdir=$prefix/lib/$compiler --libsubdir=$abi/$libname --docdir=/nix/store/fknpbrv35n2q50vi3v2zpv2nj876pcm3-hpython-0.3-doc/share/doc/hpython-0.3 --with-gcc=clang --package-db=/private/tmp/nix-build-hpython-0.3.drv-0/package.conf.d --ghc-options=-j4 --disable-split-objs --enable-library-profiling --profiling-detail=exported-functions --disable-profiling --enable-shared --disable-coverage --enable-static --disable-executable-dynamic --enable-tests --disable-benchmarks --enable-library-vanilla --disable-library-for-ghci --extra-include-dirs=/nix/store/kzy1iwh4gzr7vmjxrhdsjskf669lv6hk-libc++-7.1.0/include --extra-lib-dirs=/nix/store/kzy1iwh4gzr7vmjxrhdsjskf669lv6hk-libc++-7.1.0/lib --extra-include-dirs=/nix/store/c875qj8msbvpg8sfydmhzqnr6gss6wl2-libc++abi-7.1.0/include --extra-lib-dirs=/nix/store/c875qj8msbvpg8sfydmhzqnr6gss6wl2-libc++abi-7.1.0/lib --extra-include-dirs=/nix/store/nlqpghfkxzyqq1bxs9p23rdp9yvzk2im-compiler-rt-7.1.0-dev/include --extra-lib-dirs=/nix/store/mshpn1faxg6wmgfqr8hqzjppiga9fjml-compiler-rt-7.1.0/lib --extra-lib-dirs=/nix/store/1jl5kvjxhg1dxj9k1c0h4mpviqqcn3bi-ncurses-6.2/lib --extra-lib-dirs=/nix/store/wcflg7c7g0x31q7bb1lrhihpwib766lx-libffi-3.3/lib --extra-lib-dirs=/nix/store/kc53sx9c0ahzng2kbk7znchbmfw3hk54-gmp-6.2.0/lib --extra-include-dirs=/nix/store/6gq75lkpsr8gzdjsyg4vxiphim3474y5-libiconv-osx-10.12.6/include --extra-lib-dirs=/nix/store/6gq75lkpsr8gzdjsyg4vxiphim3474y5-libiconv-osx-10.12.6/lib --extra-framework-dirs=/nix/store/xg39313vgzbkxky11m4ghi88xp86q9gw-swift-corefoundation/Library/Frameworks
Using Parsec parser
Configuring hpython-0.3...
CallStack (from HasCallStack):
  die', called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:1022:20 in Cabal-3.0.1.0:Distribution.Simple.Configure
  configureFinalizedPackage, called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:475:12 in Cabal-3.0.1.0:Distribution.Simple.Configure
  configure, called at libraries/Cabal/Cabal/Distribution/Simple.hs:625:20 in Cabal-3.0.1.0:Distribution.Simple
  confHook, called at libraries/Cabal/Cabal/Distribution/Simple/UserHooks.hs:65:5 in Cabal-3.0.1.0:Distribution.Simple.UserHooks
  configureAction, called at libraries/Cabal/Cabal/Distribution/Simple.hs:180:19 in Cabal-3.0.1.0:Distribution.Simple
  defaultMainHelper, called at libraries/Cabal/Cabal/Distribution/Simple.hs:116:27 in Cabal-3.0.1.0:Distribution.Simple
  defaultMain, called at Setup.hs:2:8 in main:Main
Setup: Encountered missing or private dependencies:
digit ==0.7.*,
generic-lens >=1.0 && =0.5 && =4 && =6.3 && =0.7.4 && =1 && builder for '/nix/store/64j47mjb87ynnlrb7wghxqydxap80n6k-hpython-0.3.drv' failed with exit code 1
error: build of '/nix/store/64j47mjb87ynnlrb7wghxqydxap80n6k-hpython-0.3.drv' failed

Please let me know if you have any thoughts! (And of course, let me know if I should take this over to nixpkgs.)

Many thanks!