anchor.diff: -{ coreutils, fetchurl, db, openssl, pcre, perl, pkgconfig, stdenv }:
  +{ coreutils, db, fetchurl, openldap, openssl, pcre, perl, pkgconfig, stdenv
  +, enableLDAP ? false
  +}:
   
   stdenv.mkDerivation rec {
     name = "exim-4.90";
  
positive.code:       s:^# \(RM_COMMAND\)=.*:\1=${coreutils}/bin/rm:
        s:^# \(TOUCH_COMMAND\)=.*:\1=${coreutils}/bin/touch:
        s:^# \(PERL_COMMAND\)=.*:\1=${perl}/bin/perl:
        #/^\s*#.*/d
        #/^\s*$/d
      ' < src/EDITME > Local/Makefile
  
negative.code:   };
  
    nativeBuildInputs = [ pkgconfig ];
    buildInputs = [ coreutils db openssl pcre perl ]
      ++ stdenv.lib.optional enableLDAP openldap;
  
    preBuild = ''
      sed '
  