anchor.diff:      };
       lldb = fetch {
         repo = "swift-lldb";
  -      sha256 = "09x3d3bc6rn9g6jpi3fb120c4r2carsmqla4bq4scjrs0867jz9m";
  +      sha256 = "1d0pa7xm289bjb6r52hkkmlngkqkwbwgixnmm30bin2q18mkxk7s";
       };
       llbuild = fetch {
         repo = "swift-llbuild";
  
positive.code: }:
  
  let
    v_major = "4.1";
    version = "${v_major}-RELEASE";
    version_friendly = "${v_major}";
  
    tag = "refs/tags/swift-${version}";
    fetch = { repo, sha256, fetchSubmodules ? false }:
  
negative.code:     };
      foundation = fetch {
        repo = "swift-corelibs-foundation";
        sha256 = "1bhrag63rmz41bg2g6ap01qrdpq37hislgf5hg6myy2v69q7mahx";
      };
      libdispatch = fetch {
        repo = "swift-corelibs-libdispatch";
  