43539053.2.less

test {
    left-etc {
        .FluidGutter(margin, 1, 2, 3, 4);
    }
    
    vert-horz {
        .FluidGutter(padding, @v: 22, @h: 33);
    }
    
    all {
        .FluidGutter(shredder, @all: 42);
    }
}

// impl.:
.FluidGutter(@p, @t:0, @r:0, @b: 0, @l:0, @v: 0, @h: 0, @all: 0) {
    // match if tlrb = 0 and all is not
    .-(0, 0, 0, 0) when not(@all = 0) {
        .DummyMakeGutter(@p, @all @all @all @all);
    }

    // match if tlrb = 0 and vh are not
    .-(0, 0, 0, 0) when not(@v = 0) or not(@h = 0) {
        .DummyMakeGutter(@p, @v @h @v @h);
    }

    // match if neither of above matches
    .-(...) when (default()) {
        .DummyMakeGutter(@p, @t @r @b @l);
    }

    .-(@t, @r, @b, @l);
    // ^ mixin body is scoped so `.-` is usually fine
    // even if you already have `.-` elsewhere
}

.DummyMakeGutter(@p, @value) {
    @{p}: @value;
}