少css，无法正确编译

Question

我试图将一个较少的文件编译成css，但是当我尝试在这里编译这段代码时：

.colors() {
  .-("Maroon",#800000);
.-("Red",#FF0000);
.-("Orange",#FFA500);
.-("Yellow",#FFFF00);
.-("Olive",#808000);
.-("Green",#800000);
.-("Purple",#800080);
.-("Fuchsia",#FF00FF);
.-("Lime",#00FF00);
.-("Teal",#008080);
}


.icons(){
  .-("icon-adjust", "\f042");
  .-("icon-adn", "\f170");
  .-("icon-align-center", "\f037");
  .-("icon-align-justify", "\f039");
  .-("icon-align-left", "\f036");
  .-("icon-align-right", "\f038");
  .-("icon-ambulance", "\f0f9");
  .-("icon-anchor", "\f13d");
  .-("icon-android", "\f17b");
  .-("icon-angellist", "\f209");
  .-("icon-angle-double-down", "\f103");
  .-("icon-angle-double-left", "\f100");
  .-("icon-angle-double-right", "\f101");
}

.easyUI {
  .colors();
  .-(@color_,@bgColor)
{@color: e(@color_);
&.@{color} {
  background: @bgColor;
  color: contrast(@bgColor);
  border: 1px solid darken(@bgColor, 20%);
  &:hover {
    background: darken(@bgColor, 8%);
    border: 1px solid darken(@bgColor, 15%);
  }
}
}
.icons();
.-(@icon_,@content)
{@icon: e(extractor(@icon_));
&.@{icon} {
  &.prepend:before {
    font-family: fontAwesome;
    content: @content;
    margin-right: 10px;
  }
  &.append:after {
    font-family: fontAwesome;
    content: @content;
    margin-left: 10px;
  }
}
}
}

失败了，我收到了这个错误：

  

SyntaxError：错误评估函数darken：Object＃has   没有方法＆＃39; toHSL＆＃39;

为什么呢？对此有何解释？

非常感谢