# Programming Languages mini-HOWTO

## Risto S. Varanka

Jul 22nd 2000

A brief comparison of major programming languages for Linux and major libraries for creating graphical user interfaces (GUIs) under Linux

## 1. Introduction

- 1.1 Latest Version of the Document
- 1.2 Copyright
- 1.3 License
- 1.4 Disclaimer
- 1.5 Author
- 1.6 Credits
- 1.7 Links

## 2. Programming Languages

- 2.1 Concepts in the Table
- 2.2 Major Languages
- 2.3 Shell Programming
- 2.4 Other Languages
- 2.5 Links

## 3. GUI Toolkits

- 3.1 Concepts in the Table
- 3.2 Major GUI Toolkits
- 3.3 Links

## 1. Introduction

Linux is a fascinating operating system because it lets any user participate in its development. The variety of available languages, however, can be confusing to beginning Linux developers. This document lists the most common options for everyday development and states some key facts about them. (Well, ``most common'' and ``key'' as I perceive them.)

My aim is neither to review the languages nor to determine which one is the best. Each language is a tool that fits some jobs and some tastes. You can get further (often conflicting) information easily, if you ask around or keep your ears open. The Links sections in this document will give you some pointers for your own research.

There is a plethora of languages and libraries for Linux, so this document only covers the most common languages and GUI (Graphical User Interface) toolkits at the moment. This document is intended to be fairly neutral, but I haven't included all languages available. Since my judgment is undoubtedly biased in many ways, I advise serious developers to check out the sites that do a better job in listing all languages and libraries. Also note that only the Linux implementations of the languages and GUI toolkits are covered, their features on other platforms are not discussed or implied.

This document is a recent addition to the LDP, so there has not been opportunity for much community feedback. However, it is released in hopes that it will prove useful for people interested in programming under Linux, especially beginners. A question mark in the tables indicates lack of information. If you can fill it in, please contact the author.

## 1.1 Latest Version of the Document

You can find the latest modifications at http://www.helsinki.fi/~rvaranka/Computer/Linux/HOWTO/

## 1.2 Copyright

Copyright (c) 2000 Risto Varanka.

## 1.3 License

The following license terms apply to all LDP documents, unless otherwise stated in the document. The LDP documents may be reproduced and distributed in whole or in part, in any medium physical or electronic, provided that this license notice is displayed in the reproduction. Commercial redistribution is permitted and encouraged. Thirty days advance notice via email to the author(s) of redistribution is appreciated, to give the authors time to provide updated documents.

### Requirements of Modified Works

All modified documents, including translations, anthologies, and partial documents, must meet the following requirements:

1. The modified version must be labeled as such.
2. The person making the modifications must be identified.
3. Acknowledgement of the original author must be retained.
4. The location of the original unmodified document be identified.
5. The original author's (or authors') name(s) may not be used to assert or imply endorsement of the resulting document without the original author's (or authors') permission.

In addition it is requested that:

1. The modifications (including deletions) be noted.
2. The author be notified by email of the modification in advance of redistribution, if an email address is provided in the document.

As a special exception, anthologies of LDP documents may include a single copy of these license terms in a conspicuous location within the anthology and replace other copies of this license with a reference to the single copy of the license without the document being considered ``modified'' for the purposes of this section.

Mere aggregation of LDP documents with other documents or programs on the same media shall not cause this license to apply to those other works.

All translations, derivative documents, or modified documents that incorporate any LDP document may not have more restrictive license terms than these, except that you may require distributors to make the resulting document available in source format.

## 1.4 Disclaimer

THIS DOCUMENT COVERS A LARGE AND CONSTANTLY CHANGING DOMAIN. THEREFORE, THE INFORMATION CONTAINED IN THIS DOCUMENT MAY BE INCORRECT OR OUTDATED. ALL USE OF THIS DOCUMENT AND ALL INFORMATION CONTAINED IN IT IS AT YOUR OWN RISK. THE AUTHOR DOES NOT GIVE ANY WARRANTY OR GUARANTEE, EITHER EXPLICIT OR IMPLIED.

## 1.5 Author

You are welcome to send feedback to the author at: risto.varanka@helsinki.fi.

Author's web site can be found at http://www.helsinki.fi/~rvaranka/.

## 1.6 Credits

I am thankful to several people who commented on language issues. These conversations have given me a better view of the different languages, and I hope future conversations will allow this mini-HOWTO to mature over time. Especially I would like to thank the people at the IRCNet channel #linux: Morphy, Bluesmurf, Vadim, Zonk^, Rikkus and others whose names I have forgotten. Thanks go also to Stig Erik Sandoe for helpful comments.

## 1.7 Links

Exhaustive lists of Linux development libraries and tools:

- Freshmeat
- Linux Development Tools
- linuxprogramming.com

The Hacker FAQ by Eric S. Raymond is another interesting text for novice Linux developers. It concentrates on some cultural and psychological aspects of open source development.

Other LDP documents covering general programming subjects include the Reading List HOWTO and the Linux Programmer's Guide - several more have been written on specific subjects.

## 2. Programming Languages

C, Lisp and Perl are traditional hacking languages in the GNU/Linux culture; Python, PHP, Java and C++ have gained new ground recently.

## 2.1 Concepts in the Table

Language

  A common name of the language.

Beginner

  Indicates how well suited the language is for people with little programming experience. A language marked with ``yes'' should be viable for a beginner's first programming language.

Performance

  How fast your applications are likely to run when you put them into production use. Performance depends more on your algorithmic programming skills than the actual language. As a rule of thumb, C, C++ and Fortran are sometimes necessary because they can offer better performance than other languages - at other times they might be unwieldy for the desired purpose. (One idea for unscientific ``benchmarking'' of the languages would be to implement a simple sorting algorithm in all of them and compare running times. This of course does not measure the performance of the actual language - since that concept does not make sense - but only the implementation. Of course it's also not a very reliable or thorough method, but it would give an example how running times in different languages can differ. Anybody want to help me with this?)

OOP, Object-Oriented Programming vs. other paradigms

  Object-oriented programming is an important programming paradigm that is gaining popularity. In object oriented programming, data structures and algorithms are integrated into units, often called classes. OOP is often contrasted with procedural programming (which uses separate algorithms and data structures). It is not strictly dependent on language: you can do OOP in languages not listed as such (C for example), and program in the procedural style in languages that are listed as OOP. I've listed as OOP languages that have special features or add-ons to facilitate OOP. Functional languages (Lisp for example) are a bit different breed - among other things, functional programming is a superset of OOP. Logic programming (Prolog), also called declarative programming, on the other hand, is not related to the other types of programming in a similar sense.

RAD, Rapid Application Development

  More dependent on the tools you are using than the actual language. There is a HOWTO on GUI development tools for Linux, although it's out of date. With a good graphical tool you can do RAD. RAD can be powerful when based on code reuse as well, so free software could provide a good starting point.

Examples

  Mentions fields of programming the language is most often used in. Other good (and bad) uses exist, but they are less typical.

Comments

  Additional information on the language, like capacities and dialects.

## 2.2 Major Languages

    Perl
    Beginner: Yes - OOP: Yes
    Examples: Scripting, sysadmin, www
    Comments: Powerful for handling text and strings

    Python
    Beginner: Yes - OOP: Yes
    Examples: Scripting, application scripting, www
    Comments:

    TCL
    Beginner: Yes - OOP: No
    Examples: Scripting, sysadmin, applications
    Comments:

    PHP
    Beginner: Yes - OOP: Yes
    Examples: Www
    Comments: Popular for web databases

    Java
    Beginner: Yes - OOP: Yes
    Examples: Cross-platform applications, www
    Comments: Spreading to new areas, eg. e-commerce infrastructure

    Lisp
    Beginner: Yes - OOP: Functional
    Examples: Emacs modes (for Elisp), AI
    Comments: Variants Elisp, Clisp and Scheme

    Fortran
    Beginner: No  - OOP: No
    Examples: Mathematical (scientific) applications
    Comments: Variants f77 and f90/95

    C
    Beginner: No  - OOP: No
    Examples: System programming, applications
    Comments:

    C++
    Beginner: No  - OOP: Yes
    Examples: Applications
    Comments:

## 2.3 Shell Programming

Shells are an important programming environment, too. I haven't covered them because I don't understand the field very thoroughly yet. Knowledge of shells is important for anyone who works on Linux regularly, more so for system administrators. There are similarities between shell programming and other kinds of scripting - often they can achieve the same goals, and you have the option of choosing between native shell and a separate scripting language. Among the most popular shells are bash, tcsh, csh, ksh and zsh. You can get basic information on your shell with the man command, man bash for example.

## 2.4 Other Languages

Other languages of note: AWK, SED, Smalltalk, Eiffel, Ada, Prolog, assembler, Objective C, Logo, Pascal (p2c converter)

## 2.5 Links

- A general info site on programming languages, lots of info and opinions
- TCL
- Perl
- Python
- PHP
- Java
- clisp

## 3. GUI Toolkits

The standard graphical subsystem for UNIX and Linux, called X, has its own libraries for GUI development. They provide a low-level programming interface to X, but tend to be hard to use. Old end-user applications and other toolkits of course make good use of them. Nowadays the Linux GUI scene is dominated by GTK+ and Qt, since two popular, complete user environments - GNOME and KDE - are based on them.

## 3.1 Concepts in the Table

Library

  Common name or abbreviation of the toolkit.

Beginner

  Whether the toolkit is suitable for a newbie programmer.

License

  Different licenses for different GUI toolkits have practical significance. GTK+, TK and GNUstep licenses allow you to develop both open source and closed source applications without paying for a license. Motif license requires payment, while the QT license requires payment only if you write closed source programs.

Language

  The language that is most often used with the toolkit.

Bindings

  Other languages which can use the toolkit.

Examples

  Applications that use the toolkit.

Comments

  Additional information on the toolkit.

## 3.2 Major GUI Toolkits

Library | Beginner | License | Language | Bindings | Examples | Comments
TK | Yes | Free | TCL | Perl, Python, others | make xconfig, TKDesk |
GTK+ | No | Free (LGPL) | C | Perl, C++, Python, many others | GNOME, Gimp | Very popular
QT | No | Free for open source | C++ | Python, Perl, C, others? | KDE | Very popular
Motif | No | Non-free | C/C++ | Python, others? | Netscape, Wordperfect | Lesstif isa free replacement
GNUstep | No | Free (LGPL) | Objective C | Guile, Java? | None widely known, but see the application list | GNUstep is still under development

## 3.3 Links

- TK
- GTK+
- QT
- Motif
- GNUstep