Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.0)
// ----

$simple-map: (
  key1: value1,
  key2: value2
);
$complex-map: (
  sub-map1: (
    key1: value1-1,
    key2: value1-2
  ),
  sub-map2: (
    key1: value2-1,
    key2: value2-2
  ),
  sub-map3: (
    key1: value3-1,
    key2: value3-2
  )
);

.simple-map {
  $keys: map-keys($simple-map);
  @each $key in $keys {
    #{$key}: map-get($simple-map, $key);
  }
}
.complex-map {
  $keys: map-keys($complex-map);
  @each $key in $keys {
    .#{$key} {
      $submap: map-get($complex-map, $key);
      $subkeys: map-keys($submap);
      @each $subkey in $subkeys {
        #{$subkey}: map-get($submap, $subkey);
      }
    }
  }
}

SassMeister-output.css

.simple-map {
  key1: value1;
  key2: value2; }

.complex-map .sub-map1 {
  key1: value1-1;
  key2: value1-2; }
.complex-map .sub-map2 {
  key1: value2-1;
  key2: value2-2; }
.complex-map .sub-map3 {
  key1: value3-1;
  key2: value3-2; }