Source PostScript (eqstring.pps)

/eqstring {
3 dict begin
   /str2 exch def
   /str1 exch def
   str1 length str2 length eq {
      /i 0 def
      true
      str1 length {
         str1 i get str2 i get eq and
         /i i 1 add store
      } repeat
   } {
      false
   } ifelse
end
} def