Def as @ bs == Case of as; nil  bs ; a.as'  cons(a; (as' @ bs))  (recursive)

is mentioned by

Thm* l,ll:'a List. mt(l @ ll)  mt(l) & mt(ll)	[mt_append]
Def append == l1:'a List. l2:'a List. l1 @ l2	[happend]
Def flatten(l) == if null(l) then nil else head(l) @ flatten(tl(l)) fi  Def (recursive)	[flatten]

In prior sections: list 1

Try larger context: HOLlib IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html