Advanced Programming Languages Test 1

john von neumann

proposed computers be permanently hardwired with a small set of general operations

• 1940

programming language

concept for communicating WHAT we want a computer to do

assembly language

set of mnemonic symbols for instruction codes and memory locations

• ex: LD R1, FIRST

assembler

program that translates assembly language code to binary machine code

loader

program that loads machine code into computer memory

fortran, formula translation language

__ __ __ popular with scientists/engineers due to its support for algebraic notation and floating numbers

algol

---

language that provided standard notation for computer scientists to publish algorithms in journals

• 1960

• first language to receive a formal definition, including a grammar

• achieve machine independence by requiring an ___ compiler with each type of hardware

compiler

translates programming language statements into machine code

data abstraction

simplifies the behavior and attributes of data for humans

control abstraction

simplifies the properties of the transfer of control

interpreter

directly executes instructions without converting them into machine code

semantics

meaning of a language

• describes the effects of executing the code

syntax

similar to the grammar of a natural language; structure

basic data abstraction

hides internal representation of data values

structured data abstraction

groups components from basic data abstractions into a unit

unit data abstraction

data values and the operations that act on those values

• provide reusability

• usage of classes

basic control abstraction

statements that combine machine instructions into an abstract statement easier to understand

• a = b + c, x += 10

structured control abstraction

grouping instructions into blocks of codes

unit control abstraction

standalone collection of procedures

• threads, processes, tasks

efficiency

effectiveness in which resources (time, space, memory) are utilized in algorithms and programming

regularity

how well the features of a language are integrated

greater when:

• fewer restrictions on use of particular constructs

• fewer strange interactions between constructs

• fewer surprises in general in the language

• helps make programs more readable and maintainable

generality

achieved by avoiding special cases in the availability or use of constructs, and by combining closely related constructs into a single more general one

• in c++, you cannot directly compare 2 structures with ==

orthogonality

constructs can be combined in any way, with no unexpected restriction or behaviors

example: function return types

• pascal only allows scalar or pointer types as return values

• c and c++ allow values of all data types except array types

• ada and python allow all data types

uniformity

the consistency of appearance or behavior of language constructs

programmer efficiency

how quickly and easily a person can read and write in a programming language

execution efficiency

primary design criterion; amount of computational resources used by the algorithm

language success

• achieves the goals of the designer

• attains widespread use in an application area

• serves as model for other languages that are successful

principle of least astonishment

languages that satisfy the criterion of regularity are said to adhere to this

prime concerns of early language design

program speed and memory usage

function

a rule that associates to each x from set of X of values a unique y from a set Y of values

domain

the set of X

range

the set of Y

independent variable

the x in f(x), representing any value from the set X

dependent variable

the y from the set Y, defined by y=f(x)

functional programming

provide a uniform view of programs as function, and treat them as data

• simpler semantics and model of computation

referential transparency

a function given the same input will always produce the same output without causing any side effects

example:

def add(a, b):

return a + b

first-class data value

functions can be computed by other functions or parameters to other functions

tail recursion

when the recursive steps are the last steps in any function

delayed evaluation

in languages with an applicative order evaluation rule, all parameters to user-defined functions are evaluated at the time of a call

value semantics

names are only associated to values, not memory locations

• when you pass a variable to a function, it passes a copy of the value, not the reference to the value