Prolog with two new predicates: "dif" for coroutines and "freeze" for delayed evaluation. Available from ExperIntelligence, Santa Barbara CA. ["Prolog II Reference Manual and Theoretical Model", A. Colmerauer, Internal Report, GroupeIA, U Aix-Marseille (Oct 1982)].

In addition suitable contents:
[ 2 ] [ ai ] [ al ] [ an ] [ ar ] [ at ] [ au ] [ B ] [ b ] [ ba ] [ bar ] [ C ] [ CA ] [ ca ] [ cat ] [ co ] [ de ] [ E ] [ ed ] [ ee ] [ er ] [ era ] [ es ] [ et ] [ evaluation ] [ fo ] [ for ] [ fr ] [ free ] [ freeze ] [ G ] [ ge ] [ gen ] [ h ] [ IA ] [ il ] [ in ] [ io ] [ it ] [ la ] [ li ] [ lu ] [ M ] [ Mars ] [ Mode ] [ na ] [ nc ] [ ne ] [ nu ] [ O ] [ Oc ] [ om ] [ pe ] [ port ] [ pr ] [ Prolog ] [ re ] [ ro ] [ routine ] [ S ] [ se ] [ T ] [ th ] [ tw ] [ ua ] [ up ] [ va ] [ ye ]