Definitions list 1 Sections StandardLIB Doc
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Some definitions of interest.
firstnDef firstn(n;as)
Def == Case of as; nil  nil ; a.as'  if 0<n a.firstn(n-1;as') else nil fi
Def (recursive)
Thm* A:Type, as:A List, n:. firstn(n;as A List
int_isegDef {i...j} == {k:ik & kj }
Thm* i,j:. {i...j Type
lengthDef ||as|| == Case of as; nil  0 ; a.as'  ||as'||+1  (recursive)
Thm* A:Type, l:A List. ||l||  
Thm* ||nil||  

About:
listconsnillist_ind
ifthenelseintnatural_numberaddsubtractset
recursive_def_noticeuniversememberandall
!abstraction
IF YOU CAN SEE THIS go to /sfa/Nuprl/Shared/Xindentation_hack_doc.html

Definitions list 1 Sections StandardLIB Doc