anchor.diff:  
   let
     options = rec {
  -    /* TODO: there are also MacOS, FreeBSD and Windows versions */
  +    /* TODO: there are also FreeBSD and Windows versions */
       x86_64-linux = {
         arch = "linuxx86";
         sha256 = "0hs1f3z7crgzvinpj990kv9gvbsipxvcvwbmk54n51nasvc5025q";
  
positive.code:       runtime = "armcl";
        kernel = "linuxarm";
      };
      armv6l-linux = armv7l-linux;
    };
    cfg = options.${stdenv.system};
  
negative.code:     sha256 = cfg.sha256;
    };
  
    buildInputs = if stdenv.isDarwin then [ m4 ] else [ gcc glibc m4 ];
  
    CCL_RUNTIME = cfg.runtime;
    CCL_KERNEL = cfg.kernel;
  
    postPatch = if stdenv.isDarwin then ''
      substituteInPlace lisp-kernel/${CCL_KERNEL}/Makefile \
        --replace "M4 = gm4"   "M4 = m4" \
        --replace "dtrace"     "/usr/sbin/dtrace" \
        --replace "mig"        "/usr/bin/mig" \
        --replace "/bin/rm"    "${coreutils}/bin/rm" \
        --replace "/bin/echo"  "${coreutils}/bin/echo"
  
      substituteInPlace lisp-kernel/m4macros.m4 \
        --replace "/bin/pwd" "${coreutils}/bin/pwd"
    '' else ''
      substituteInPlace lisp-kernel/${CCL_KERNEL}/Makefile \
        --replace "/bin/rm"    "${coreutils}/bin/rm" \
        --replace "/bin/echo"  "${coreutils}/bin/echo"
  