MELJUN CORTES Programming_languages_Introduction to Programming Languages

8/8/2019 MELJUN CORTES Programming_languages_Introduction to Programming Languages

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Introduction to Programming Languages

Programming Languages

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Classes of Programming

Languages

Imperative Languages

Block-Structured or Procedural Languages

Object-Oriented Languages

Languages for Distributed Programming

Declarative Languages

Functional or Applicative Languages Logic Programming

Languages for Databases


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Reasons for Studying


To understand the language you are using

To understand the significance ofprogramming constructs andimplementation

To make it easier to learn a new language

To know which programming language touse

To design a new language easier


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Language Evaluation

Criteria

Readability

the quality of a language that enables a

programmer to understand and comprehendthe structure of programs so that they can

be easily understood and read

Factors affecting readability:

Simplicity

Orthogonality

Control Statement Design

Syntax


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Language Evaluation

Criteria

Writability

measure of how easily and conveniently a

language can be used to create codes orprograms for a particular problem

Factors affecting writability:

Simplicity

Orthogonality

Abstraction


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Language Evaluation

Criteria

Reliability

the ability of a program to perform to its

specifications under all-possible conditionsor circumstances

Factors affecting reliability:

Type checking

Exception Handling

Aliasing

Readability

Writability


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Language Evaluation

Criteria

haracteristics of ost

Programmer training

Software creation

Compilation

Execution

Compiler cost

Poor reliability.

Maintenance


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Influences on

Language Design

Computer Architecture

Most of the popular languages of the last 45

years have been designed around theprevalent von Neumann architecture

These languages are called imper tivel ngu ges

von Neumann computer architecture basics:• stores data and program in the same memory,

while the CPU which executes instructions is

separate from memory • instructions and data must be piped from

memory to the CPU and the results moved back to memory

central features of imperative languages are:• variables which model the memory cell

• assignment statements based on the pipingoperation

• operands in expressions are piped frommemory to the CPU, and the result ofevaluating the expression is piped back to thememory cell representing the left side of theassignment

• the iterative form of repetition

• instructions are stored in adjacent cells in

memory so iteration is fast in this architecture


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Influences on

Language Design

Programming Methodologies

1950s and early 1960s: Simple applications

– worry about machine efficiency Late 1960s: People efficiency became

important – readability and better controlstructures

Late 1970s:• Top-design and stepwise refinement

• Discovery of incompleteness of type checking

and inadequacy of control statements Middle 1980s: Object-oriented programming

• Added inheritance and dynamic method binding which enhance the potential reuse ofexisting software


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Implementation

Methods

Processor

composed of circuits that execute a set of

machine instructions, or macroinstructions Internal Memory

used by the processor to store data andinstructions

Layered View of a Computer


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Compilation

translates high-level language programsinto equivalent programs in machine

language

COMPILER

Analysis

Synthesis


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Pure Interpretation

A method of software simulation whichtranslates high-level language programs by

interpreting them through softwaresimulation of a computer, using high-levellanguage.

Advantage:

allow easy implementation of many source-

level debugging operations

Disadvantages:

slow execution

requires more space


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Hybrid Implementation

Systems

source programs into intermediate code-like versions and then decode and

accomplish them through interpretation

Intermediate

CodeGenerator Interpreter Results

Parse Trees Intermediate Code

MELJUN CORTES Programming_languages_Introduction to Programming Languages

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