anchor.diff:  
     # Splicer will pull out correct variations
     libDeps = platform: stdenv.lib.optional enableTerminfo [ ncurses ]
  +    ++ [libffi]
       ++ stdenv.lib.optional (!enableIntegerSimple) gmp
       ++ stdenv.lib.optional (platform.libc != "glibc" && !targetPlatform.isWindows) libiconv;
   
  
positive.code: , autoconf, automake, coreutils, fetchurl, fetchpatch, perl, python3, m4, sphinx
  
  , libiconv ? null, ncurses
  
  , useLLVM ? !stdenv.targetPlatform.isx86 || (stdenv.targetPlatform.isMusl && stdenv.hostPlatform != stdenv.targetPlatform)
  , # LLVM is conceptually a run-time-only depedendency, but for
  
negative.code:   configureFlags = [
      "--datadir=$doc/share/doc/ghc"
      "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
    ] ++ stdenv.lib.optionals (libffi != null) ["--with-system-libffi" "--with-ffi-includes=${libffi}/include" "--with-ffi-libraries=${libffi}/lib"
    ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && !enableIntegerSimple) [
      "--with-gmp-includes=${targetPackages.gmp.dev}/include" "--with-gmp-libraries=${targetPackages.gmp.out}/lib"
    ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc" && !targetPlatform.isWindows) [
  