{ writeText, stdenv, dovecot_pigeonhole, ... } @ pkgs: { name, src, exts }:
let dummyConfig = writeText "dovecot.cfg" ''
  plugin {
    sieve_plugins = sieve_imapsieve sieve_extprograms
    sieve_global_extensions = +vnd.dovecot.pipe
  }
'';
in
stdenv.mkDerivation {
  inherit name;
  inherit src;

  phases = [ "copyPhase" "compilePhase" ];

  copyPhase = ''
    mkdir $out
    cp $src $out/${name}.sieve
    chmod 0755 $out/${name}.sieve
    set +x
  '';
  compilePhase = ''
    ${dovecot_pigeonhole}/bin/sievec -c ${dummyConfig} $out/${name}.sieve $out/${name}.svbin -x "${toString exts}"
  '';
}