Lecture 5 - Page 6 : 26
Functional Programming in Scheme
The Order of Evaluation
* Referential transparency
Referential transparency
An illustration of referential transparency
* Introduction to evaluation order
Arbitrary evaluation order - with some limits
A motivating example
A motivating example - clarification
* Rewrite rules, reduction, and normal forms
Rewrite rules
The alpha rewrite rule
The beta rewrite rule
The eta rewrite rule
Normal forms
The ordering of reductions
An example of normal versus applicative evaluation
Theoretical results
Practical implications
Conditionals and sequential boolean operators
Lazy evaluation
* Delayed evaluation and infinite lists in Scheme
Delayed evaluation in Scheme
Examples of delayed evaluation
Infinite lists in Scheme: Streams
Example streams
Stream example: The sieve of Eratosthenes
Applications of The sieve of Eratosthenes
A motivating example
What is the value of the following expression?
((lambda (x) 1)
some-infinite-calculation
)
A constant function with an actual parameter expression, the evaluation of which never terminates.
A more concrete version of the expression from above.
The function
infinite-calculation
just calls itself without ever terminating.