1.1.8 Procedures as Black-Box Abstractions

Question 1

When is a procedure regarded to be black-box?

Answer 1

When at any given moment, we are not concerned with how the procedure computes its result, but only with the fact that it computes it.

Question 2

procedural abstraction

Answer 2

The level of abstraction in which the details of how a procedure is computed can be suppressed, to be considered at a later time.

Question 3

abstraction in Computer Science

Answer 3

A concept that a user should not need to know how a procedure is implemented in order to use it.

Question 4

bound variable (in procedures)

Answer 4

The name of a formal parameter in a procedure, which does not change the meaning of a procedure definition even when consistently renamed throughout the definiton

Question 5

scope of a name

Answer 5

The set of expressions in which a name is defined or valid. In a procedure definition, the bound variables have the body of the procedure as their scope and will not have any meaning outside of it.

Question 7

free variable (in procedures)

Answer 7

Variables or names within a procedure that are not bound to the procedure and have meaning outside of the procedure body.

Question 8

block structure

Answer 8

Nesting of definitions that provides a solution to the simplest name-packaging problem.

Question 9

free variable (in procedures)

Answer 9

Variables or names within a procedure that are not bound to the procedure and have meaning outside of the procedure body.

Question 9

lexical scoping

Answer 9

Allows inner procedures to access variables defined in their enclosing procedures without the need for explicit parameter passing.