ALGOL 68 Genie: Difference between revisions
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After successful parsing of an entire source program, the syntax tree, that serves as an intermediate program representation, is interpreted. The interpreter performs many runtime checks.
The author of Algol 68 Genie is Marcel van der Veer. Algol68G is released under
[[ALGOL 68G]] is an interpretor that runs on Linux and a good way to get started with [[ALGOL 68]]. ''ALGOL 68G'' mk14.1 is now available for download for Fedora9 from Source Forge - [http://sourceforge.net/project/showfiles.php?group_id=114223&package_id=300114&release_id=642308 Download now]. (This download RPM includes a 400 page [[ALGOL 68]] manual in printer ready pdf)
==Features of Algol68G==
* The [[interpreter]] performs checks on many events, for example: assigning to <
* Precision of numeric modes: implementation of <
* On systems that support them, UNIX extensions that allow e.g. for executing child processes that communicate through pipes, matching regular expressions or fetching web page contents.
* Procedures for drawing using the GNU Plotting Utilities.
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== Extensions to Algol 68 ==
* Implementation of C.H. Lindsey's partial parametrisation proposal, which allows for [[currying]] in Algol 68, giving it a functional sublanguage.
* A simple refinement preprocessor to facilitate top-down program construction.
* Implementation of pseudo-operators <
* Implementation of a post-checked loop. A do-part may enclose a serial clause followed by an optional until-part, or just enclose an until-part. This is an alternative to the paradigm Algol 68 post-check loop <
* Implementation of <
== Deviations from the Revised Report language ==
The important deviations are:
* The important difference with the Revised Report transput model is that Algol68G transput does not operate on <
* The Algol68G parallel clause deviates from the Algol 68 parallel clause when parallel clauses are nested. In Algol68G, stack frames inside a parallel unit are private, therefore if parallel units modify a shared variable then this variable must be declared outside the outermost parallel clause, and a jump out of a parallel unit can only be targeted at a label outside the outermost parallel clause.
* The interpreter does not implement so-called ghost-elements {RR 2.1.3.4}, hence it cannot check bounds when assigning to rows of mode flexible-rows-of-rows-of-... when the destination has a flat descriptor.
* Algol68G does not recognise nonlocal environs {RR 5.2.3.2}. All environs are local.
* Transputting a file is essentially sequential. Only <
* When all arguments in a call of <
==
Note that to use large arrays, the amount of memory available for the interpreter can be set via the "heap" command line parameter or via a "heap" pragmatic comment.
<pre>
E.g.: via the command line:
a68g -heap=512M someProgram.a68
E.g.: Using a pragmatic comment in the actual Algol 68 source:
PR heap=512M PR
</pre>
==Download==
* [http://www.xs4all.nl/~jmvdveer/algol.html Algol 68 Genie web page]
* [http://sourceforge.net/projects/algol68/ Fedora/Centos/RHEL/Win32: Sourceforge Algol 68 Compiler, Interpreter & Runtime]
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