alternate.scss

$dark-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$light-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$login-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$utility-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$search-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$websearch-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$default-button-style:
  hover-border #abcdef,
  hover-background #abcdef,
  hover-text #abcdef,
  hover-text-shadow #abcdef,
  hover-gradient-1 #abcdef,
  hover-gradient-2 #abcdef;

$button-styles:
  dark $dark-button-style,
  light $light-button-style,
  login $login-button-style,
  utility $utility-button-style,
  search $search-button-style,
  websearch $websearch-button-style,
  default $default-button-style;

@function lookup($map, $key) {
  @foreach $pair in $map {
    @if $key == nth($pair, 1) {
      @return nth($pair, 2);
    }
  }
}

@mixin button-hover($type) {
  $style: lookup($button-styles, $type);
  @include button-style(
    lookup($style, hover-border),
    lookup($style, hover-background),
    lookup($style, hover-text),
    lookup($style, hover-text-shadow),
    lookup($style, hover-gradient-1),
    lookup($style, hover-gradient-2));
}

refactor.scss

$button-styles:
  dark ($darkButtonHoverBorder,
        $darkButtonHoverBackground,
        $darkButtonHoverText,
        $darkButtonHoverTextShadow,
        $darkButtonHoverGradient1,
        $darkButtonHoverGradient2),
  light ($lightButtonHoverBorder,
         $lightButtonHoverBackground,
         $lightButtonHoverText,
         $lightButtonHoverTextShadow,
         $lightButtonHoverGradient1,
         $lightButtonHoverGradient2),
  login ($loginButtonHoverBorder,
         $loginButtonHoverBackground,
         $loginButtonHoverText,
         $loginButtonHoverTextShadow,
         $loginButtonHoverGradient1,
         $loginButtonHoverGradient2),
  utility ($utilityButtonHoverBorder,
           $utilityButtonHoverBackground,
           $utilityButtonHoverText,
           $utilityButtonHoverTextShadow,
           $utilityButtonHoverGradient1,
           $utilityButtonHoverGradient2),
  search ($searchButtonHoverBorder,
          $searchButtonHoverBackground,
          $searchButtonHoverText,
          $searchButtonHoverTextShadow,
          $searchButtonHoverGradient1,
          $searchButtonHoverGradient2),
  websearch ($websearchButtonHoverBorder,
             $websearchButtonHoverBackground,
             $websearchButtonHoverText,
             $websearchButtonHoverTextShadow,
             $websearchButtonHoverGradient1,
             $websearchButtonHoverGradient2),
  default ($defaultButtonHoverBorder,
           $defaultButtonHoverBackground,
           $defaultButtonHoverText,
           $defaultButtonHoverTextShadow,
           $defaultButtonHoverGradient1,
           $defaultButtonHoverGradient2);

@mixin button-hover($type) {
  @foreach $pair in $button-styles {
    @if $type == nth($pair, 1) {
      $style: nth($pair, 2);
      @include button-style(
        nth($style, 1),
        nth($style, 2),
        nth($style, 3),
        nth($style, 4),
        nth($style, 5),
        nth($style, 6));
    }
  }
}