Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.3.14)
// Compass (v1.0.1)
// ----

@mixin button($background: blue) {
  background: $background;
  border: 1px solid darken($background, 5%);
}

$buttons:(
  primary:(
    background: blue
  ),
  secondary:(
    background: green
  )
);

@each $type in map-keys($buttons) {
  .button-#{$type} {
    $button-color: map-get(map-get($buttons, $type), background);

    @include button($button-color);
  }
}

SassMeister-output.css

.button-primary {
  background: blue;
  border: 1px solid #0000e6;
}

.button-secondary {
  background: green;
  border: 1px solid #006700;
}