Generated by SassMeister.com.

SassMeister-input.scss

// ----
// Sass (v3.4.5)
// Compass (v1.0.1)
// ----

@function map-deep-merge($map1, $map2) {
  $return: $map1;

  @each $key, $value in $map2 {
      
    @if map-get($return, $key) != null and type-of($value) == map and type-of(map-get($return, $key)) == map {
      $value: map-deep-merge(map-get($return, $key), $value);
    }
        
    $return: map-merge($return, ($key: $value));
  }

  @return $return;
}

@each $yup, $nope in map-get(
  map-deep-merge((
    foo: (
      bar: bar,
      bat: bat
    )
  ), (
    foo: (
      cat: cat,
      bar: yup
    )
  )), foo) {
  .#{$yup}-#{$nope} {display:none;}
}

SassMeister-output.css

.bar-yup {
  display: none;
}

.bat-bat {
  display: none;
}

.cat-cat {
  display: none;
}