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A Guide for the AsmetaL syntax

March 2026

The AsmM concrete syntax (AsmetaL) is a textual notation to be used by modelers to effectively write ASM models within the ASMETA framework. It is defined in terms of an EBNF (extended Backus-Naur Form) grammar derived from a semantic interpretation of the AsmM metamodel (the abstract syntax).

The AsmetaL language can be divided roughly into four parts: the structural language (provides the constructs required for describing the structure of an ASM model.), the definitional language (provides the basic definitional elements such as functions, domains, rules and axioms characterizing an algebraic specification), the language of terms (provides all kinds of syntactic expressions which can be evaluated in a state of an ASM), and the behavioral language or the language of rules (provides a notation to specify the transition rule schemes of an ASM).

This quick guide gives a description of each part by presenting the notation in an intuitive style for better readability, instead of reporting the grammar productions. For a more formal definition see the EBNF grammar.

Note that, to write an ASM model of a system, the file containing the ASM spec must contain a single ASM structure definition and take the ".asm" extension (e.g. MyAsmModel.asm).

Index

  1. Notational conventions
  2. Structure of an ASM
  3. Domain declarations
  4. Function declarations
  5. Terms
  6. Transition rules
  7. Syntactic rules on ID names
  8. Comments

Notational Conventions

In this guide the following conventions are adopted:

  • the AsmM concrete syntax appears in red text

  • keywords appear in bold face

  • a pair of square braces (not in bold face) is not considered part of the concrete notation, it indicates only that the enclosed expression is optional

  • the notation as in t1,...,tn indicates one or more elements.

Syntactic rules on ID names

We use the following rules to distinguish among names of domains, functions, enumeration elements, rules, variables:

ID_VARIABLE a string beginning with the dollar sign "$"; $x $abc

ID_ENUM a string of length greater than or equal to two and consisting of upper-case letters only; ON OFF RED

ID_DOMAIN a string beginning with an upper-case letter; Integer X SetOfBags Person

ID_RULE a string beginning with the lower-case letter "r" followed by the underscore symbol "_"; r_SetMyPerson r_update

ID_FUNCTION a string beginning with a lower-case letter, but not starting with "r_"; plus minus re

Comments

Comments can be written as follows:

// text to be commented

/ text to be commented/