@import "for";
@list-y: 'I', 'You', 'others';
.for(@list-y); .-each(@type) {
  @y-class: ~'.y-@{type}';
  @{y-class} {
    y: @type;
  }
}

@import "for";
@list-x: 'less', 'cirious', 'somebody', 'somebody-else';
.for(@list-x); .-each(@type) {
  @x-class: ~'.x-@{type}';
  @{x-class} {
    x: @type;
  }
}

@import "x";
@import "y";

$ lessc both.less
.x-less {
  x: 'less';
}
.y-less {
  y: 'less';
}
.x-cirious {
  x: 'cirious';
}
.y-cirious {
  y: 'cirious';
}
...
.x-I {
  x: 'I';
}
.y-I {
  y: 'I';
}
...

$ lessc -v
lessc 1.7.5 (Less Compiler) [JavaScript]