sub sum{ ( shift()//return 0 ) + &sum }

print sum( 1,2,3);;
6

print sum( 1 .. 100 );;
Deep recursion on subroutine "main::sum" at
5050

##</code><code>##

print Y( sub{my$rec=shift; sub{(shift()//return 0) + &$rec }})->(1 .. 100);;
5050

##</code><code>##

sub Y {
    my ( $curried_rec ) = @_;
    sub {
        my ( $f1 ) = @_;
        $curried_rec->( sub { $f1->( $f1 )->( @_ ) } )
    }->( sub {
        my ( $f2 ) = @_;
        $curried_rec->( sub { $f2->( $f2 )->( @_ ) } )
    } )
}

##</code><code>##

C:\test>perl -Mstrict -wE"say eval join'+',()"


C:\test>perl -Mstrict -wE"say eval join'+',0"
0

C:\test>perl -Mstrict -wE"say eval join'+',-1"
-1

C:\test>perl -Mstrict -wE"say eval join'+',-1..+3"
5