The Meta-Environment

A guide to The Meta-Environment documentation for newbies

This pages serves as an index to the documentation on The Meta-Environment for people that are completely new to it. There are a few things to learn before starting to use it:

• Syntax definition and parsing using SDF.
• Algebraic specification and term rewriting using ASF+SDF.
• The particular usage of The Meta-Environment IDE.

If you have not attended the course already, you should start reading the Introductory slides on ASF+SDF, which feature all three issues.

If you are interested in documentation on RScript (relational calculus), look here. An index to all documentation can be found here. The MailingLists are used by users and developers to help each other.

Syntax definition and parsing using SDF

Syntax definition is the task of defining the syntax of a language using grammar production rules. From this definition a parser can be generated that transforms source code (an input sentence) to a tree. So, the user of The Meta-Environment defines a syntax and The Meta-Environment generates a parser for her. The language to define syntax in The Meta-Environment is called SDF (similar to EBNF).

• First read A quick introduction to syntax analysis (8 pages) to understand the concepts of syntax definition and parsing.
• Possibly review the introductory slides again regarding SDF.
• Then read the example syntax definition of the Boolean language and the example syntax definition of the Pico programming language, which are part of this manual: Writing Language Definitions in ASF+SDF. If you understand this definition, you are ready to start using SDF.
• Use The SDF reference manual to look up details about SDF when needed.
• Browse through the online guided tour to learn how the use the IDE to start editing SDF modules. Some part of the guided tour already refers to algebraic specification and term rewriting, which you may ignore.

For troubleshooting:

• Parse errors can be hard to debug. There is no online manual on that subject. Use general debugging techniques to find the cause of the failure:
  • limit the size of the input as much as possible
  • use delta debugging to find the minimal difference between a sentence that parses and one that does not.
  • keep in mind that the error is either in the input sentence, or in the SDF definition.
• Ambiguities can be debugged using the method described here.

Algebraic specification and term rewriting using ASF+SDF

The other formalism next to SDF in The Meta-Environment is called ASF+SDF. You can manipulate the trees produced by parsers generated from SDF definitions using ASF+SDF. This is done using a form of programming called algebraic specification which is similar to the functional programming paradigm in many ways. An ASF program is actually a rewriting system, which simply transforms trees to other trees.

• First read A quick introduction to term rewriting to understand the concepts of algebraic specification and term rewriting.
• Possibly review the introductory slides again regarding [ASF+SDF.
• The re-read the example definition of the Boolean language for some example rewrite rules.
• Study some slightly more complex ASF+SDF programs in ASF+SDF by example. They all consist of an SDF part and an ASF part, so make sure to have read the documentation on SDF first.
• Browse through the online guided tour to learn how the use the IDE to start editing ASF+SDF modules.
• Use the ASF+SDF reference manual to look up details about ASF+SDF when needed.

For troubleshooting:

• Explanation of ASF error messages
• When something 'does not rewrite' you could use the (somewhat experimental) debugger for ASF+SDF. Instead of 'Reduce' choose 'Debug Reduce' in the IDE, and go to the 'Processes' tab in the left part of the IDE. Then right-click on a process in the list to activate a source viewer. Use the 'step into' and 'step over' buttons to find the part of your program that fails.