$ perl -wle'$x=0+Infinity; print $x; print $x<=>0'
inf
1

$ perl -wle'$x=0-Infinity; print $x; print $x<=>0'
-inf
-1

$ perl -wle'$x=0+NaN; print $x; print $x<=>0'
nan
Use of uninitialized value in print at -e line 1.