Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.12)
// Compass (v1.0.3)
// ----

$colors-list: width height border margin;
.foo {
@each $current-color in $colors-list {
    $i: index($colors-list, $current-color) * .5s;
    transition: $current-color $i;
}
}

SassMeister-output.css

.foo {
  transition: width 0.5s;
  transition: height 1s;
  transition: border 1.5s;
  transition: margin 2s;
}