<p>Question: </p>

<pre><code>((lambda (x y) (x y)) (lambda (x) (* x x)) (* 3 3))
</code></pre>

<p>This was #1 on the midterm, I put "81 9" he thought I forgot to cross one out lawl, so I cross out 81, and he goes aww. Anyways, I dont understand why it's 81.</p>

<p>I understand why <code>(lambda (x) (* x x)) (* 3 3) = 81</code>, but the first lambda I dont understand what the x and y values are there, and what the <code>[body] (x y)</code> does.</p>

<p>So I was hoping someone could explain to me why the first part doesn't seem like it does anything.</p>

This needs some indentation to clarify
```
```
((lambda (x y) (x y))
 (lambda (x) (* x x))
 (* 3 3))
```
```
```
(lambda (x y) (x y))
```
; call
```
x
```
with
```
y
```
as only parameter.
```
(lambda (x) (* x x))
```
; evaluate to the square of its parameter.
```
(* 3 3)
```
; evaluate to 9
So the whole thing means: "call the square function with the 9 as parameter".
EDIT: The same thing could be written as
```
```
((lambda (x) (* x x))
 (* 3 3))
```
```
I guess the intent of the exercise is to highlight how evaluating a scheme form involves an implicit function application.