We don't need outermost parentheses\. \(We can write $~$\\lambda x.(\\lambda y.(x+y))$~$ instead of $~$(\\lambda x.(\\lambda y.(x+y)))$~$\.\) Application is, by default, left associative\. \($~$f\\ x\\ y$~$ means "the function $~$f$~$ with inputs $~$x$~$ and $~$y$~$," i\.e\. $~$(f\\ x)\\ y$~$, not $~$f\\ (x\\ y)$~$\.\) The scope of any $~$\\lambda$~$ is as large is possible\. \($~$\\lambda x.\\lambda y.x+y$~$ means $~$\\lambda x.(\\lambda y.(x+y))$~$, not $~$(\\lambda x.\\lambda y.x)+y$~$ or $~$\\lambda x.(\\lambda y.x)+y$~$ or anything like that\.\) We can abbreviate sequences of $~$\\lambda$~$s\. \(As mentioned before, we can write $~$\\lambda xy.x+y$~$ for $~$\\lambda x.\\lambda y.x+y$~$\.\)

I think this sentence would be easier to read without the parenthesis around the second sentence.