documentclass{standalone}
usepackage{pgfmath,pgffor}
begin{document}
defnames{{"Katie","Frank","Laura","Joe"}}%
newcounter{lines}%
setcounter{lines}{3}%
defarr{1,arabic{lines}}%

foreach i in arr {%
  Name i: pgfmathparse{names[i]}pgfmathresult, }

end{document}

letarr@empty

defaddtolist#1#2{%
  lst@lAddTo#1{#2}}

addtolist{arr}{arabic{lines}}