Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.5.4)
// ----

$themes: (
  light: (
    text: black
  ),

  dark: (
    text: white
  )
);

@mixin themify($prop, $key, $themeList: $themes) {
  @each $themeName ,$theme in $themeList {
    $value: map-get($theme, $key);
    .#{$value} {
      #{$prop}: $value;
    } 
  }
}

.foo {
  display: flex;
  @include themify('color', 'text');
}

SassMeister-output.css

.foo {
  display: flex;
}

.foo .black {
  color: black;
}

.foo .white {
  color: white;
}