▁context ▁where ▁one ▁of ▁type ▁A ▁is ▁expected ▁( cov ari ant ), ▁even ▁if ▁the ▁reverse ▁is ▁not ▁true . ▁Like ▁equivalence , ▁the ▁sub type ▁relation ▁is ▁defined ▁differently ▁for ▁each ▁programming ▁language , ▁with ▁many ▁variations ▁possible . ▁The ▁presence ▁of ▁paramet ric ▁or ▁ad ▁h oc ▁polym orphism ▁in ▁a ▁language ▁may ▁also ▁have ▁imp lications ▁for ▁type ▁compatibility . ▁ ▁See ▁also ▁▁▁ ▁Com parison ▁of ▁type ▁systems ▁ ▁Cov ar iance ▁and ▁contra var iance ▁( comput er ▁science ) ▁ ▁Pol ym orphism ▁in ▁object - orient ed ▁programming ▁ ▁Type ▁rules ▁ ▁Type ▁signature ▁ ▁Type ▁theory ▁ ▁Notes ▁ ▁References ▁ ▁Further ▁reading ▁ ▁External ▁links ▁▁▁▁▁ ▁Smith , ▁Chris , ▁What ▁to ▁Know ▁Before ▁Deb ating ▁Type ▁Systems ▁▁▁ ▁Category : Data ▁types ▁Category : Program ▁analysis ▁Category : Type ▁theory <0x0A> </s> ▁Peter ▁Gabriel ▁Car val ho ▁Car ab allo ▁( born ▁ 2 5 ▁September ▁ 1 9 9 2 ) ▁is ▁a ▁Portuguese ▁footballer ▁who ▁plays ▁for ▁Am ora ▁FC ▁as ▁a ▁forward . ▁He ▁also ▁holds ▁Uruguay an ▁citizens hip . ▁ ▁Football ▁career ▁On ▁ 2 ▁August ▁ 2 0 1 5 , ▁Car ab allo ▁made ▁his ▁professional ▁debut ▁with ▁Oriental ▁in ▁a ▁ 2 0 1 5 – 1 6 ▁Ta ça ▁da ▁Liga ▁match ▁against ▁F ream unde . ▁ ▁References ▁ ▁External ▁links ▁ ▁Category : 1 9 9 2 ▁birth s ▁Category : S ports people ▁from ▁La us anne ▁Category : L