Quintus Prolog, DEC-10 Prolog, SICstus Prolog, and other similar Prolog systems offer only two methods of input:

  1. reading Prolog terms using read/1
  2. reading single characters using get0/1

There is a large gap between the two, and sometimes the input requirements of application programs lies in the gap. The Prolog library contains two sets of packages to fill the gap.