▁part ▁of ▁the ▁GNU ▁Project ▁and ▁is ▁free ▁software , ▁available ▁under ▁the ▁terms ▁of ▁the ▁GNU ▁General ▁Public ▁License ▁( G PL ). ▁ ▁History ▁H ai ble ▁did ▁not ▁originally ▁intend ▁to ▁dist ribute ▁CL IS P ▁under ▁the ▁G PL , ▁but ▁in ▁a ▁well - public ised ▁email ▁exchange ▁with ▁Richard ▁St all man , ▁he ▁eventually ▁agreed ▁to ▁do ▁so . ▁The ▁issue ▁at ▁st ake ▁was ▁whether ▁CL IS P ▁was ▁a ▁derivative ▁work ▁of ▁the ▁GNU ▁read line ▁library . ▁ ▁Port s ▁CL IS P ▁is ▁extremely ▁port able , ▁running ▁on ▁almost ▁all ▁Unix - based ▁operating ▁systems ▁as ▁well ▁as ▁on ▁Microsoft ▁Windows . ▁Although ▁interpre ting ▁byte code ▁is ▁usually ▁slower ▁than ▁running ▁compiled ▁native ▁bin aries , ▁this ▁is ▁not ▁always ▁a ▁major ▁issue ▁( es pecially ▁in ▁applications ▁like ▁Web ▁development ▁where ▁I / O ▁is ▁the ▁bott l ene ck ). ▁CL IS P ▁is ▁also ▁easier ▁to ▁set ▁up ▁than ▁other ▁popular ▁FO SS ▁Common ▁Lis ps ▁such ▁as ▁S BC L . ▁ ▁A do ption ▁Paul ▁Graham ▁used ▁CL IS P ▁to ▁run ▁the ▁software ▁for ▁his ▁Via web ▁startup . ▁Via web ▁was ▁an ▁early ▁web ▁application ; ▁port ions ▁of ▁it ▁still ▁exist ▁as ▁Y ahoo ! ▁St ores , ▁the ▁base ▁for ▁Y ahoo ▁Sho pping . ▁ ▁Con rad ▁Bar ski ' s ▁Land ▁of ▁L isp ▁uses ▁some ▁CL IS P - specific ▁functions ▁in ▁the ▁text book ▁exer cis es