1. Issued: Monday, February 7 2. To Be Completed By: Friday, February 18, 6: 00 PM

Most people learn more effectively when they study in small groups and cooperate in various other ways on homework. This can be particularly true in programming assignments, where working with a partner often helps to avoid careless errors. We are very much in favor of this kind of cooperation, so long as all participants actively involve themselves

Closed book- one sheet of notes hroug hout this quiz, we have set aside space in which you should write your answers. Please try to put all of answers in the designated spaces, as we will look only in this spaces when grading

Evaluation and universal machines The Eval/Apply Cycle What is the role of evaluation in defining a language? Eval and Apply execute a cycle that unwinds our abstractions Reduces to simple applications of built in

Abstraction Elements of a Language(or Engineering Design) Primitives, means of combination means of abstraction What weve seen Procedural Abstraction. ambda-captures common patterns and Deep question

Slide 32.1.1 We have spent some time looking at computational objects that rency and asynchronous computing are built around the use of local state variables and methods for Object oriented approaches lose \referential transparency Referential transparency means equal expressions

Slide 17.5.1 Streams-a different way of structuring Now, let's look at one example in which changing the computation evaluation model allows us to explore a very different kind of computational problem. Our goal is to show how a smal

signment exp en ((definition? exp)(eval-definition exp env)) ((if? exp)(eval-if exp env)) ((lambda? exp) (make-procedure (lambda-parameters exp)(lambda-body exp) env)) ((begin? exp)(eval-sequence (begin-actions exp)env)

1. Arithmetic calculator 6 (define (eval exp) 8 ((number? exp) exp) ((sum? exp (eval-sum exp))

Slide 15.1.1 Why do we need an interpreter? Our goal over the next few lectures is to build an interpreter which in a very basic sense is the ultimate in programming, since doing so will allow us to define our language