anchor.diff:          name = "postgrest-hsie-graph-modules";
           docs = "Create a PNG graph of modules imported within the codebase.";
         }
  -      ''${hsie} graph-modules main src | ${graphviz}/bin/dot -Tpng -o "$1"'';
  +      ''
  +        outfile="''${1:?outfile not set}"
  +        ${hsie} graph-modules main src | ${graphviz}/bin/dot -Tpng -o "$outfile"
  +      '';
   
     hsieGraphSymbols =
       checkedShellScript
  
positive.code:         name = "postgrest-hsie-graph-symbols";
          docs = "Create a PNG graph of symbols imported within the codebase.";
        }
        ''${hsieMinimalImports} graph-symbols | ${graphviz}/bin/dot -Tpng -o "$1"'';
  in
  buildEnv {
    name = "postgrest-devtools";
  
negative.code:         inRootDir = true;
        }
        ''
          dumpdir="''${1:?dumpdir not set}"
          tmpdir="$(mktemp -d)"
          mkdir -p "$dumpdir"
          ${cabal-install}/bin/cabal v2-build ${devCabalOptions} \
  