;; Let's call this language Purple (makes it easy to refer to)
;; This language is an expansion of the lambda calculus with 
;; 1. lambda expressions with 0 or more parameters
;; 2. procedure applications with 0 or more parameters
;; 3. Numbers!

;; This is the concrete syntax for Purple

 <exp>    ::==  
	  |  <number>
	  |  <varref>
	  |  (lambda (<var>*) <exp>)
	  |  (<exp>+)