Example of a simple Sass mixin to create a background gradient with progressive error handling and introspection

getListValue.sass

@function get-list-value($list, $place: first)
  $list-length: length($list)
  $group: null
  @if $place == first
    $group: nth($list, 1)
  @else if $place == last
    $group: nth($list, length($list))

  $listValue-object: nth($group, 1)
  @return $listValue-object

implementation.sass

my-selector
  +simple-gradient(bottom, #fffadc 0%, #53cbf1 40%, #05abe0 100%)

simpleGradient.sass

=simple-gradient($direction, $colors...)
  $startColorstr: get-list-value($colors)
  $endColorstr: get-list-value($colors, last)

  background-color: $startColorstr
  background-image: linear-gradient(to $direction, $colors)
  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr = '#{ie-hex-str($startColorstr)}', endColorstr = '#{ie-hex-str($endColorstr)}', GradientType = 0)

simpleGradientWithIntrospection.sass

=simple-gradient($direction, $colors...)
  @if function-exists(get-list-value)
    $startColorstr: get-list-value($colors)
    $endColorstr: get-list-value($colors, last)

    background-color: $startColorstr
    background-image: linear-gradient(to $direction, $colors)
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr = '#{ie-hex-str($startColorstr)}', endColorstr = '#{ie-hex-str($endColorstr)}', GradientType = 0)
  @else
    @warn "The `simple-gradient' mixin requires the custom function 'get-list-value', please install"

simpleGradientWithMoreErrorhandling.sass

=simple-gradient($direction, $colors...)
  @if function-exists(get-list-value)
    $startColorstr: get-list-value($colors)
    $endColorstr: get-list-value($colors, last)
    @if type-of($startColorstr) == color
      @if type-of($endColorstr) == color
        background-color: $startColorstr
        background-image: linear-gradient(to $direction, $colors)
        filter: progid:DXImageTransform.Microsoft.gradient(startColorstr = '#{ie-hex-str($startColorstr)}', endColorstr = '#{ie-hex-str($endColorstr)}', GradientType = 0)
      @else
        @warn "'#{$endColorstr}' is an invalid color, ignoring use in the '#{&}' selector"
    @else
      @warn "'#{$startColorstr}' is an invalid color, ignoring use in the '#{&}' selector"
  @else
    @warn "The `simple-gradient' mixin requires the custom function 'get-list-value', please install"