Precedences for Conctypes

We consider again a user defined syntax feature, the conctype, which is a new datatype construction. An embedded language can easily be introduced into a programming language using conctypes, and computations are easily expressed using the concrete syntax and a special pattern matching form. Context-free grammars serve as a basis for the definition of the new syntax. A problem that is investigated in this paper is how to use precedences to resolve ambiguity. The way precedences are used in LR-parsers is sometimes unnatural and is hard to translate to other parsing techniques. We isolate one kind of ambiguity which can be resolved with precedence rules and show that it is easy for a user to augment a grammar with precedence rules. We define the generated language for such a grammar in terms of an attribute grammar and show that it is easy to automatically construct a parser that recognizes the language. 1 Conctypes In a previous paper [APS88] we described a user defined syntax featu..