▁language ▁should ▁ad here ▁to ▁the ▁Don ' t ▁repeat ▁yourself ▁( DR Y ) ▁principle . ▁It ▁should : ▁ ▁A void ▁unnecessary ▁repet itions ▁ ▁F ocus ▁on ▁clean ▁code ▁ ▁Well - indent ed ▁Mark up ▁language ▁with ▁good ▁ind entation ▁impro ves ▁appearance , ▁makes ▁it ▁easy ▁to ▁read ▁for ▁readers ▁and ▁also ▁to ▁determine ▁where ▁a ▁given ▁element ▁starts ▁and ▁ends . ▁ ▁Clear ▁structure ▁Mark up ▁language ▁with ▁a ▁clear ▁structure ▁will ▁help ▁in ▁code ▁maintenance ▁and ▁logical ▁understanding ▁of ▁final ▁result . ▁It ▁is ▁unclear ▁whether ▁Ham l ▁offers ▁any ▁differential ▁advantage ▁in ▁this ▁regard . ▁ ▁Ex amples ▁Ham l ▁markup ▁is ▁similar ▁to ▁CSS ▁in ▁syntax . ▁For ▁example , ▁Ham l ▁has ▁the ▁same ▁dot ▁. ▁representation ▁for ▁classes ▁as ▁CSS ▁does , ▁making ▁it ▁easy ▁for ▁developers ▁to ▁use ▁this ▁markup . ▁ ▁" Hello , ▁World !" ▁ ▁Ham l ▁as ▁a ▁command - line ▁tool ▁The ▁following ▁are ▁equivalent ▁as ▁H AML ▁recogn ises ▁CSS ▁select ors : ▁% p {: class ▁=> ▁" sample ", ▁: id ▁=> ▁" wel come "} ▁Hello , ▁World ! ▁% p . sample # wel come ▁Hello , ▁World ! ▁ ▁These ▁render ▁to ▁the ▁following ▁HTML ▁code : ▁< p ▁class =" sample " ▁id =" wel come "> Hello , ▁World ! </ p > ▁ ▁Ham l ▁as ▁an ▁add - on ▁for ▁Ruby ▁on ▁Rails ▁To ▁use ▁Ham l ▁with ▁Ruby , ▁the ▁Ruby ▁Gem file ▁should ▁include