The purpose of this paper is twofold. Firstly we show how attributes in an attribute grammar can be simply and efficiently evaluated using a lazy functional language. The class of attribute grammars we can deal with are the most general ones possible: attributes may depend on each other in an arbitrary way, as long as there are no truly circular data dependencies. Secondly, we describe a methodology based on attribute grammars, where, in a fairly straightforward way, we can develop efficient functional programs where direct, conventional solutions yield less efficient programs. We review two examples from a paper by R. Bird (Using circular programs to eliminate multiple traversals of data, Acta Informatica, 21, 1984) where he transforms simple but inefficient multipass programs into more efficient single pass ones, but which on their own can be very hard to understand. We show how such efficient but tangled programs can have natural formulations as attribute grammars. We also propose a...

An attribute grammar is a declarative specification of dependence among computations carried out at the nodes of a tree. Attribute grammars have proven remarkably difficult to decompose into logical fragments. As a result, they have not yet been accepted as a viable specification technique. By combining the ideas of remote attribute access and inheritance, we have been able to define "attribution modules" that can be reused in a variety of applications. As an example, we show how to define reusable modules for name analysis that embody different scope rules. 1 Introduction A fairly standard decomposition of the compiler construction task has evolved over the past twenty years, and most compilers have very similar structures. Many of the subproblems defined by the standard decomposition can be described as computations over trees, in which information is attached to individual tree nodes and used to control various decisions. 22 For example, consider the subproblem of determining t...

Higher Order Attribute Grammars (HAGs) are an extension of normal attribute grammars in the sense that the distinction between the domain of parse-trees and the domain of attributes has disappeared: parse trees may be computed in attributes and grafted to the parse tree at various places. As a result semantic functions may be described by attribute evaluation.

Abstract. Forwarding is a technique for providing default attribute definitions in attribute grammars that is helpful in the modular implementation of programming languages. It complements existing techniques such as default copy rules. This paper introduces forwarding, and shows how it is but a small extension of standard higher-order attribute grammars. The usual tools for manipulating higher-order attribute grammars, including the circularity check (which tests for cyclic dependencies between attribute values), carry over without modification. The closure test (which checks that each attribute has a defining equation) needs modification, however, because the resulting higher-order attribute grammars may contain spurious attributes that are never evaluated, and indeed that need not be defined. 1

We present a technique to prevent the construction of intermediate data structures in functional programs, which is based on results from the theory of tree transducers. We first decompose function definitions, which correspond to macro tree transducers, into smaller pieces. Under certain restrictions...

. Two well-known formalisms for the specication and computation of tree transductions are compared: the mso graph transducer and the attributed tree transducer with look-ahead, respectively. The mso graph transducer, restricted to trees, uses monadic second order logic to dene the output tree in terms of the input tree. The attributed tree transducer is an attribute grammar in which all attributes are trees; it is preceded by a look-ahead phase in which all attributes have nitely many values. The main result is that these formalisms are equivalent, i.e., that the attributed tree transducer with look-ahead is an appropriate implementation model for the tree transductions that are speciable in mso logic. This result holds for mso graph transducers that produce trees with shared subtrees. If no sharing is allowed, the attributed tree transducer satises the single use restriction. 1 Introduction Formulas of monadic second order (mso) logic can be used to express properti...

Many functional programs with accumulating parameters are contained in the class of macro tree transducers. We present a program transformation technique that can be used to solve the efficiency problems due to creation and consumption of intermediate data structures in compositions of such functions, where classical deforestation techniques fail. In order to do so, given two macro tree transducers under appropriate restrictions, we construct a single macro tree transducer that implements the composition of the two original ones. The imposed restrictions are more liberal than those in the literature on macro tree transducer composition, thus generalising previous results.

. Aspect-oriented programming provides the programmer with means to cross-cut conventional program structures, in particular the class hierarchies of object-oriented programming. This paper studies the use of aspect orientation in structuring syntax directed compilers implemented as attribute grammars. Specifically, it describes a method for specifying definitions of related attributes as `aspects' and treating them as first-class objects, that can be stored, manipulated and combined. It is hoped that this embedding of an aspect-oriented programming style in Haskell provides a stepping stone towards a more general study of the semantics of aspect-oriented programming. 1 Introduction Compilers are often structured by recursion over the abstract syntax of the source language. For each production in the abstract syntax, one defines a function that specifies how a construct is to be translated. The method of structuring compilers in this syntax--directed manner underlies the for...

The paper describes the MAX system, a tool for specification and prototyping of language processors. The MAX system is based on a first--order framework generalizing attribute grammar like frameworks. It allows to refer to syntax tree nodes and "distant" attribute occurrences. Attributes may have tree nodes as values, so that global relations between distant tree nodes can be expressed. This enables more compact and readable specifications for a wide class of complex problems. Within the presented framework, context conditions can be globally formulated by first--order predicate formulae. The paper explains the fundamental semantical concepts of the system, shows its application to a small name analysis problem, and describes the main implementation issues. In particular, we present a powerful attribute evaluation algorithm that can handle attribute dependencies arising during evaluation time. Finally, we report on the experiences made by the system and compare it to other s...

Generic control operators, such as fold, have been introduced in functional programming to increase the power and applicability of data-structure-based transformations. This is achieved by making the structure of the data more explicit in program specifications. We argue that this very important property is one of the original concepts of attribute grammars. In this paper, we informally show the similarities between the fold formalism and attribute grammar specifications. We also compare their respective method to eliminate the intermediate data structures introduced by function composition (notion of deforestation or fusion): the normalization algorithm for programs expressed with folds and the descriptional composition of attribute grammars. Rather than identify the best way to achieve deforestation, the main goal of this paper is merely to intuitively present two programming paradigms to each other's supporting community and provide an unbiased account of their similarities and diff...