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

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

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

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

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

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