A Definition of Programming Languages

Working Definition

PROGRAMMING LANGUAGES: A notational system for describing computation in machine readable and human readable form

• Low level languages

Assembler languages which are machine specific/dependent and a readable version of the machine language.

• High level languages

Various levels of abstraction can be observed.
There is a machine independent focus for general purpose languages.

PROGRAMMING LANGUAGES: A notational system for describing computation in machine readable and human readable form

• computation can be formally defined by a Turing machine

A Turing machine has an I/O tape (used for input, output and memory), 
a PushDown Automaton (PDA -- a stack),
and a Finite State Machine (FSM)

• Church's Thesis: It is not possible to build a machine that is inherently more powerful than a Turing machine

PROGRAMMING LANGUAGES: A notational system for describing computation in machine readable and human readable form

• notation in simple enough structure to translate to machine language
• study of compiler design

understanding the class of context free languages (simple enough)
in which a program can be translated in linear time (proportional to program size)

• syntax vs semantics

PROGRAMMING LANGUAGES: A notational system for describing computation in machine readable and human readable form

• natural language resemblance
• actions are abstracted for ease of understanding by humans