Line

local function line(x,y,v,l) --(v-isVertical)(l-len)
  for i=1,l do
    local xof,yof=0,0
    if v then
      yof=(i-1)+0.01
    else
      xof=(i-1)+0.01
    end
    love.graphics.points(x+xof,y+yof)
  end
end

OR
(better ad faster)

local function line(x,y,v,l,t)
  t=t or 1
  if v then
    love.graphics.rectangle('fill',x,y,t,l)
  else
    love.graphics.rectangle('fill',x,y,l,t)
  end
end