The predicates documented here are used to define a language's syntax, in terms of the meta-model of the AST used to represent programs of the language. They describe the program elements avialable as logic facts to programmers writing model analyses or conditional transformations (CTs) for this language.

Predefined predicates, expressing naming conventions for AST node arguments:

• ast_argname_id
• ast_argname_parent

Predicates that language plugin writers must define.

• ast_node_def
• ast_relation
• ast_sub_tree
• ast_ref_tree

These predicates are used by StarTransformer

• to check syntactic correctness (of CTs and of the internal representation generated by a parser)
• to define the language-independent access to and language-independent transformation of ASTs

A StarTransformer plugin for the language language is expected

• to be called st.language
• to declare the above predicates as multifile predicates
• to provide corresponding predicate definitions that mention language as the language argument