SICP: Chapter 1. Building Abstractions with Procedures

###1.1 The Elements of Programming

####1.1.1 Expressions

Prefix notation

####1.1.2 Naming and the Environment

(define [name] [value])

Defines environment(global environment)

####1.1.3 Evaluating Combinations

####1.1.4 Compound Procedures

(define (square x) (* x x))

####1.1.5 The Substitution Model for Procedure Application

Applicative order versus normal order

• normal order: fully expand and then reduce(lazy approach?)
• applicative order: (eager approach?)

####1.1.6 Conditional Expressions and Predicates

(cond (<p1> <e1>)
      (<p2> <e2>)
      ...
      (<pn> <en>))

or

(cond (<p1> <e1>)
      ...
      (else <en>))

if statement

(if <predicate> <consequent> <alternative>)

logical composition operations:

• and
• or
• not

####1.1.7 Example: Square Roots by Newton’s Method

• In mathematics we are usually concerned with declarative (what is) descriptions
• In CS we are usually concerned with imperative (how to) descriptions

####1.1.8 Procedures as Black-Box Abstractions

• Each procedure accomplishes and identifiable task that can be used as a module in defining other procedures
• Block structure: to make procedures local and make proper variables free

###1.2 Procedures and the Processes They Generate

1.2.1 Linear Recursion and Iteration

###Questions

1. Is normal order vs applicative order same as lazy evaluation vs eager evaluation
2. Exercise 1.7