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

The 6.001 Lazy Meta-Circular Evaluator The Core Evaluator (define (l-eval exp env) (cond ((self-evaluating? exp) exp) ((variable? exp)(lookup-variable-value exp env)) ((quoted? exp)(text-of-quotation exp)) ((assignment? exp)(eval-assignment exp env)) ((definition? exp)(eval-definition exp env)) ((if? exp)(eval-if exp env))

Slide 17.1.1 Normal Order(Lazy) Evaluation Over the past few lectures, we have been looking at evaluation especially how to implement eval and apply in a anguage such as Scheme, in order to define a language. What we have seen is that by creating, or specifying, eval and its associated procedures, we actually define the semantics of the

Slide 16.1.1 Building up a language Last time, we completed building our evaluator. And as you saw, we slightly misled you. We started off saying we were going to user Scheme's lexical analyzer and parser, but then build our own evaluator, which we did initially for arithmetic

Slide 15.6.1 The next stage in the evolution of our evaluator is to pull the 5. Environment as explicit parameter environment out as an explicit parameter. Up until now we could rely on just having a single environment in which to store (eva1'(pus*64)) bindings for variables. It made sense to have a global

Slide 14.4.1 Cleaning up some details of our implementation So we have seen a first pass at building an object-oriented tem, using Scheme as the base. There are a few details that The need for self-reference

Ⅱ. Listening skills How to Overcome Fears of Flying If you are afraid of flying, there are specialists who can teach you how to deal with your fears and They will find out if a nearby airport has special training programs for people who are afraid to fly. Many airports do. How would such a program work? First, a specialist will take your group to the airport to watch the planes take off and land. A

Part 1 understanding marketing management Part 2 analyzing marketing opportunities Part 3 developing marketing strategies Part 4 making marketing decisions Part 5 managing and delivering marketing programs

Slide l.l.1 This first thing we need to do is discuss the focus of 6.001 What is this course all about? This seems quite obvious-- this What is the focus of 6.001 is a course about computer science. But we are going to claim This course is about Computer Science in a rather strange way that this is not really true

Beating the Averages Paul Graham (This article is based on a talk given at the Franz Developer in Cambridge, MA, on March 25, 2001 In the summer of 1995, my friend rt morris and i started a startup called Viaweb. Our pla to write software that would let end users build online stores. What was novel about this