 The length-of-hypotenuse operation maps two positive real numbers \(x\) and \(y\) to another positive real number. One can represent such multiple-arity operations using the apparatus of the \(\lambda\)-calculus by viewing the operation as taking one input at a time. Thus, the operation can be seen as taking one input, \(x\), a positive real number, and producing as its value not a number, but an operation: namely, the operation that takes a positive real number \(y\) as input and produces as output the positive real number \(\sqrt{x^2 + y^2}\). One could summarize the discussion by saying that the operation,  hypotenuse-length, that computes the length of the hypotenuse of a right triangle given the lengths \(a\) and \(b\) of its legs, is: