Quintus Prolog, DEC-10 Prolog, SICstus Prolog, and other similar Prolog systems offer only two methods of input:
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.
library(readsent)are for reading English sentences. They return a list of words, which you can then parse using a Definite Clause Grammar (built into the Prolog system).
library(ask)are more general in purpose.