Nested loops in Less - less

Question

I have some nested loops in Less.
It should create css rules for padding with 3 sizes and 4 direction.
Code sample:
#sizes: normal, small, large;
#size-normal: 1em;
#size-small: 0.8 * #size-normal;
#size-large: 1.2 * #size-normal;
.l-padding {
#directions: top, left, right, bottom;
.s(#i: length(#sizes)) when (#i > 0) {
.s((#i - 1));
.d(#j: length(#directions)) when (#j > 0) {
.d((#j - 1));
#dir: extract(#directions, #j);
#s: extract(#sizes, #i);
#size: "size-#{s}";
&_#{dir}_#{s} {
.l-padding-mixin(#dir, ##size);
}
}
.d();
}
.s();
}
I don't know where is the problem but it compile to many duplacates. However each independet loop do their job.
.l-padding_top_normal {
padding-top: 1em;
}
.l-padding_left_normal {
padding-left: 1em;
}
.l-padding_right_normal {
padding-right: 1em;
}
.l-padding_bottom_normal {
padding-bottom: 1em;
}
.l-padding_top_normal {
padding-top: 1em;
}
.l-padding_left_normal {
padding-left: 1em;
}
.l-padding_right_normal {
padding-right: 1em;
}
.l-padding_bottom_normal {
padding-bottom: 1em;
}
.l-padding_top_normal {
padding-top: 1em;
}
...
.l-padding_top_normal {
padding-top: 1em;
}
.l-padding_top_small {
padding-top: 0.8em;
}
.l-padding_left_small {
padding-left: 0.8em;
}
.l-padding_right_small {
padding-right: 0.8em;
}
.l-padding_bottom_small {
padding-bottom: 0.8em;
}
.l-padding_top_normal {
padding-top: 1em;
}
.l-padding_left_normal {
padding-left: 1em;
}
.l-padding_right_normal {
padding-right: 1em;
}
.l-padding_bottom_normal {
padding-bottom: 1em;
}
...
To many duplicates. Can any one help with this?
UPD
thanks to #Harry find solution:
.l-padding-mixin(#direction, #size: 1em) {
padding-#{direction}: #size;
}
#sizes: normal, small, large;
#size-normal: 1em;
#size-small: 0.8 * #size-normal;
#size-large: 1.2 * #size-normal;
//==== layouts ====
.l-padding {
#directions: top, left, right, bottom;
#i: length(#sizes);
#j: length(#directions);
.d(#j) when (#j > 0) {
.d((#j - 1));
#dir: extract(#directions, #j);
#s: extract(#sizes, #i);
#size: "size-#{s}";
&_#{dir}_#{s} {
.l-padding-mixin(#dir, ##size);
}
}
.-(#i) when (#i > 0) {
.-((#i - 1));
.d(#j);
} .-(#i);
}