:perl -lne "$sum+=$_}{print $sum"
syntax error at -e line 1, near "+="
Execution of -e aborted due to compilation errors.
:perl -lne '$sum+=$_}{print $sum'
>1
>2
>3
:perl -lne '$sum+=$_}continue{print $sum'
>1
1
>2
3
>3
6
>4
10