5 <TITLE>Why Loglan'82?</TITLE>
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9 <H1><IMG src="loglanmm.gif">Why Loglan'82?</H1>
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12 We think that everybody should take acquaintance with certain
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13 features of Loglan'82. Even if you will continue to use your favorite
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14 XYZ language, you will be at least aware of what you are missing.
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16 Four features of Loglan'82 distinguish it from the other OO languages:
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18 <A NAME="mli"><STRONG>multi-level inheritance, </STRONG></A><BR>
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19 <EM> the language offers both nesting and inheritance of modules
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21 </EM>nesting enables <EM> sharing </EM>of environments and inheritance
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22 enables <EM> private copies </EM>of environments. <BR>
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23 Both methods of module's construction are useful and important!
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25 <LI><A NAME="mki"><STRONG>multi-kind inheritance </STRONG></A>
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27 <EM> e.g. a procedure can inherit from a class, <BR>
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28 </EM>making use of it one can enforce protocols, dynamically check
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29 axioms of abstract data types etc.
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30 <LI><A NAME="saf"><STRONG>SAFETY </STRONG></A><BR>
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31 - <EM>Loglan'82 signals a lot of programming errors that pass
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32 unrecognized in other systems.<BR>
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33 - </EM>There is no risk of dangling references, no confusion of
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35 <EM>Safe deallocation statement and safe storage management
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37 <LI><A NAME="conc"><STRONG>object-oriented concurrency </STRONG></A>
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39 <EM> objects of processes can be created dynamically and allocated
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40 on a processor accessible by the network <BR>
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41 </EM>The processes can communicate and synchronize through a new,
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42 powerful mechanism:<EM><B> ALIEN CALL </B></EM>
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46 Other, standard methods of OO programming are present in Loglan'82:
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48 <LI>classes and objects of classes,
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49 <LI>virtual methods,
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50 <LI>hierarchies of classes,
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51 <LI>exception handling,
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52 <LI>operators of structured programming,
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61 Loglan'82 is accompanied by an original methodology of software
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62 engineering which supports the most complicated and most expensive
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63 phases of software creation: specification, analysis and verification.
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64 There are good reasons for using Loglan'82 in:
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66 <LI><A href="#Edu">education</A>,
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67 <LI><A href="#Fast">fast prototyping of software</A>,
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68 <LI><A href="#res">research</A>.
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71 <H2><A NAME="Edu">Education</A>. </H2>
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74 The academic community has a need for one language which enables
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75 to teach all elements of object programming: classes & objects,
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76 coroutines, processes (in Loglan'82 processes are objects which
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77 are able to act in parallel), inheritance, exception handling,
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78 dynamic arrays etc. Loglan'82 offers the complete sets of programming
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79 tools used in object and modular and structural programming.
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81 It is of importance to have compilers acting in different operating
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82 environments: MS-DOS, Unix, Atari, etc. in order to assure the
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83 exchange of sources between students and teachers, between users
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84 of : personal computers, workstations and servers of university's
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85 networks. We are working on the prolongation of the list of machines
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86 and systems that support Loglan'82.
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88 Loglan'82 supports other styles of programming e.g. programming
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89 by rules, functional programming etc.
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91 The teacher and the students can use different computers (see
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92 "Machines" file) and still they can exchange the sources
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93 and to follow the experiments of others. You can distribute the
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94 files of Loglan'82 among the students which own PC/DOS, ATARI,
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95 PS2, PC/Unix. You can install Loglan'82 in your computing centre
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96 on Unix or Vax/VMS or Novell servers. You can install Loglan'82
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97 on your workstation (Sun, PC/Unix, Apollo etc.). On all machines
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98 you can compile and execute the same program. Whether it will
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99 be a student's program checked by a teacher, or an instructive
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100 program transmitted to the students. And students can work at
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101 home or in a computer room of your University.
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103 For the PC users Loglan'82 comes with an environment consisting
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104 of - lotek - a text editor integrated with compiler and other
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105 tools, - a structural editor which guides you when you do not
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106 know the syntax of Loglan'82, - an electronic manual to be used
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107 with Norton Guide or its clones,
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109 A set of instructive examples is added to the distribution package.
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111 We encourage you to experiment with the system since:
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113 <LI>you can find it useful and interesting to teach the object
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115 <LI>you can find Loglan'82 useful in fast prototyping of software,
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116 <LI>you can apply and extend several predefined classes which
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117 define and implement the problem- oriented languages extending
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118 Loglan'82 in various directions.
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121 <H2><A NAME="res">Research</A>.</H2>
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124 Loglan'82 has been used as a <EM>tool</EM> with a success in research
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127 <LI>object oriented databases,
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128 <LI>symbolic computation (computer algebra, ...),
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130 <LI>proving the properties of programs.<BR>
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135 this list is not the exhaustive one.
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137 Loglan'82 is a <EM>source</EM> of many problems of broader interest.
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139 <LI>The problem of giving one non-contradictory semantics to the
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140 language admitting both nesting of modules and inheritance from
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142 <LI>Dangling reference problem.
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143 <LI>Mathematical models of concurrent processes.<BR>
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144 Loglan'82 is the result of a research on fundamental questions
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146 <LI>Multiple inheritance and nesting.
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147 <LI>Libraries of predefined classes - how to define the meaning
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148 of separately compiled modules in the presence of nesting and
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149 multiple inheritance.
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150 <LI>The virtual Loglan'82 machine as a federation of co-processes.
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151 <LI>Execution of processes of a Loglan'82 program in a LAN of
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152 heterogeneous computers.
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153 <LI>Execution of Loglan'82 programs on parallel computers e.g.
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155 <LI>to find a complete, axiomatic definition of the notions of
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156 class and of inheritance,
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157 <LI>is it possible to make efficiently the nesting of modules
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158 and the multiple inheritance?
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159 <LI>how to manage the libraries of predefined procedures and classes
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160 in the presence of nesting?
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161 <LI>how to install the language on a real multiprocessor system?
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165 The problem 1 was solved by the team lead by A.Kreczmar in co-operation
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166 with the group of H. Langmaack.
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168 The problem 2 was solved by A.Kreczmar and was analyzed formally
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171 T.Müldner and A.Salwicki gave the Max model of parallel computations.
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172 H.-D. Burkhard proved that it differs essentially from the interleaving
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175 B. Ciesielski gave a new concept of objects of processes and a
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176 communication mechanism of alien calls of procedures. This version
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177 was implemented by him in 1988.
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179 The problems 4 - 12 are open. We would be happy to co-operate
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180 on solving them together with you.
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182 We recommend Loglan'82 as a tool to be used in the research in:
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183 object-oriented databases, development of CASE tools, VHDL, silicon
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184 compilers, simulation, etc.
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185 <H2><A NAME="Fast">Production of new software</A></H2>
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188 There are only a few languages which, like Loglan'82, enable both
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189 ways of modules' developing: nesting (- a module can be declared
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190 in other module) and inheritance (also called prefixing). The
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191 modules of your software can share the environment (by means of
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192 nesting) or they can inherit other modules as private copies of
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193 the modules declared elsewhere. The inheritance in Loglan'82 permits
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194 to inherit a module declared somewhere in the tree of nested modules.
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195 Moreover, the inheritance is no longer restricted to classes.
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196 Any module, whether it will be a class, a block, a procedure,
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197 a function, a coroutine or a process can inherit from a class.
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198 Coroutines and processes can be inherited in classes, coroutines
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199 or processes. Another kind of module is a handler. Handlers serve
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200 to handle signals (of exceptions).
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202 Altogether one can use 7 kinds of modules.
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204 The tools offered by Loglan'82 enable in various ways to create
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205 generic modules whether they are to serve as generic procedures
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206 or parameterized data types. In order to do so one can use either
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207 the possibility to pass types as formal parameters or the inheritance
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208 mechanisms. The language makes possible overloading the names
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209 of operations via the mechanism of virtual functions or procedures.
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211 This and other programming tools offered by Loglan'82 permit to
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212 quickly create a prototype of a program and to test it in a friendly
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213 environment. The compiler gives a good diagnostic of the eventual
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214 errors. For the time being we can not offer a code generator.
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215 Instead you can use the Loglan_to_C crosscompiler.
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217 The language is especially well suited for the
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219 <LI>reusability and
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220 <LI>proving the correctness.
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224 Loglan'82 supports various methods of programming:
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226 <LI>imperative - since it is a descendant of Algol, Pascal, ...
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227 <LI>object-oriented - since it is a continuation, and extension
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228 of the ingenious ideas of Simula-67,
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229 <LI>functional programming is easy,
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230 <LI>programming by rules is supported by a specialized class BACKTRACK
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231 designed and developed in Loglan'82.
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236 We would appreciate any news (comments, questions, suggestions,
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237 objections, ...) from you. Please write to Andrzej.Salwicki@univ-pau.fr
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249 <A href="http://www.univ-pau.fr/~salwicki/GMyAS.html">AS </A>08:03
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254 Pau, le 26 Janvier 1994
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projects / loglan.git / blob