Many of the examples in this manual show lists of character codes
being written as quoted strings. This actually happens if you
load the library package library(printchars). That package
extends the predicate portray/1 (using
library(addportray)) so that print/1, the top-level, and the
debugger will write lists of character codes as follows:
| ?- X = [0'a,0'b,0'c].
X = [97,98,99]
| ?- ensure_loaded(library(printchars)).
| ?- X = [0'a,0'b,0'c].
X = "abc"