open(IN, "<foo.txt");
# This line does the work.
# <IN> reads lines from the file, feeding that list to the map.
# split(/\|/, $_) creates a list of the the pipe-delimted elements
# [   ]  creates an anonymous array ref to that list.
# Finally the map returns the resulting list of array refs.
my @foo = map { [(split(/\|/, $_))] } <IN>;
close(IN);

# Just to prove that it worked.
foreach (@foo) {
                print join(' -- ', @$_), "\n";
}