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Complexity Analysis for a Lazy HigherOrder Language
 In Proceedings of the 3rd European Symposium on Programming
, 1990
"... This paper is concerned with the timeanalysis of functional programs. Techniques which enable us to reason formally about a program's execution costs have had relatively little attention in the study of functional programming. We concentrate here on the construction of equations which compu ..."
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This paper is concerned with the timeanalysis of functional programs. Techniques which enable us to reason formally about a program's execution costs have had relatively little attention in the study of functional programming. We concentrate here on the construction of equations which compute the timecomplexity of expressions in a lazy higherorder language. The problem with higherorder functions is that complexity is dependent on the cost of applying functional parameters. Structures called costclosures are introduced to allow us to model both functional parameters and the cost of their application. The problem with laziness is that complexity is dependent on context. Projections are used to characterise the context in which an expression is evaluated, and costequations are parameterised by this contextdescription to give a compositional timeanalysis. Using this form of context information we introduce two types of timeequation: sufficienttime equations and nece...
Abstract interpretation based formal methods and future challenges, invited paper
 Informatics — 10 Years Back, 10 Years Ahead, volume 2000 of Lecture Notes in Computer Science
, 2001
"... Abstract. In order to contribute to the solution of the software reliability problem, tools have been designed to analyze statically the runtime behavior of programs. Because the correctness problem is undecidable, some form of approximation is needed. The purpose of abstract interpretation is to f ..."
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Cited by 40 (6 self)
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Abstract. In order to contribute to the solution of the software reliability problem, tools have been designed to analyze statically the runtime behavior of programs. Because the correctness problem is undecidable, some form of approximation is needed. The purpose of abstract interpretation is to formalize this idea of approximation. We illustrate informally the application of abstraction to the semantics of programming languages as well as to static program analysis. The main point is that in order to reason or compute about a complex system, some information must be lost, that is the observation of executions must be either partial or at a high level of abstraction. In the second part of the paper, we compare static program analysis with deductive methods, modelchecking and type inference. Their foundational ideas are briefly reviewed, and the shortcomings of these four methods are discussed, including when they should be combined. Alternatively, since program debugging is still the main program verification
Abstract Interpretation of Functional Languages: From Theory to Practice
, 1991
"... Abstract interpretation is the name applied to a number of techniques for reasoning about programs by evaluating them over nonstandard domains whose elements denote properties over the standard domains. This thesis is concerned with higherorder functional languages and abstract interpretations with ..."
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Abstract interpretation is the name applied to a number of techniques for reasoning about programs by evaluating them over nonstandard domains whose elements denote properties over the standard domains. This thesis is concerned with higherorder functional languages and abstract interpretations with a formal semantic basis. It is known how abstract interpretation for the simply typed lambda calculus can be formalised by using binary logical relations. This has the advantage of making correctness and other semantic concerns straightforward to reason about. Its main disadvantage is that it enforces the identification of properties as sets. This thesis shows how the known formalism can be generalised by the use of ternary logical relations, and in particular how this allows abstract values to deno...
Using Projection Analysis in Compiling Lazy Functional Programs
 In Proceedings of the 1990 ACM Conference on Lisp and Functional Programming
, 1990
"... Projection analysis is a technique for finding out information about lazy functional programs. We show how the information obtained from this analysis can be used to speed up sequential implementations, and introduce parallelism into parallel implementations. The underlying evaluation model is evalu ..."
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Projection analysis is a technique for finding out information about lazy functional programs. We show how the information obtained from this analysis can be used to speed up sequential implementations, and introduce parallelism into parallel implementations. The underlying evaluation model is evaluation transformers, where the amount of evaluation that is allowed of an argument in a function application depends on the amount of evaluation allowed of the application. We prove that the transformed programs preserve the semantics of the original programs. Compilation rules, which encode the information from the analysis, are given for sequential and parallel machines. 1 Introduction A number of analyses have been developed which find out information about programs. The methods that have been developed fall broadly into two classes, forwards analyses such as those based on the ideas of abstract interpretation (e.g. [9, 18, 19, 7, 17, 12, 4, 20]), and backward analyses such as those based...
Uniform Ideals and Strictness Analysis
 In Proc. 18th Int'l Coll. on Automata, Languages and Programming (ICALP
, 1991
"... We propose a notion of uniform ideal (certain Scottclosed sets) to characterise strictness properties. This enables us to explain why Hughes' and Wadler's H projection for lazy list strictness analysis is not in general expressible as an abstract interpretation property of the standard se ..."
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We propose a notion of uniform ideal (certain Scottclosed sets) to characterise strictness properties. This enables us to explain why Hughes' and Wadler's H projection for lazy list strictness analysis is not in general expressible as an abstract interpretation property of the standard semantics. We give circumstances when it is so expressible. Doing so casts light on Burn's HB projection and his question of its relationship to H. Uniform ideals are a generalisation of the sets of values corresponding to types in (simple) polymorphic type systems. Wadler's doublylifted abstract domain constructor for lazy lists can be seen as a special case which only uses certain uniform ideals. The conuence of strictness and type theory furthers Kuo and Mishra's notion of \strictness types". Summary of results We characterise strictness properties as uniform ideals. This enables us to give abstract interpretation properties to show that a function on list(t 1 +t 2 ) is Hstrict (Wadler an...
Backward Analysis for HigherOrder Functions Using Inverse Images
, 1991
"... We propose a method for performing backward analysis on higherorder functional programming languages based on computing inverse images of functions over abstract domains. This method can be viewed as abstract interpretation done backward. Given an abstract semantics which supports forward analysis ..."
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We propose a method for performing backward analysis on higherorder functional programming languages based on computing inverse images of functions over abstract domains. This method can be viewed as abstract interpretation done backward. Given an abstract semantics which supports forward analysis, we can transform it into an abstract semantics which performs backward analysis. We show that if the original abstract semantics is correct and computable, then the transformed version of the abstract semantics is also correct and computable. More specifically, given a forward abstract semantics of a higherorder functional language which is expressed in terms of Scottclosed powerdomains, we derive an backward abstraction semantics which is expressed in terms of Scottopen powerdomains. The derivation is shown to be correct and the relationships between forward analysis and backward analysis is established. We apply this method to the classic strictness analysis in functional languages...
Optimising Compilation  Part II: lazy functional languages
, 1992
"... : This lecture considers the optimisation of functional programming languages (particularly `lazy' languages) based on `strictness analysis'. Such optimisations alter evaluation order to allow more efficient translation into von Neumann architecture or to increase the parallelism in a sequ ..."
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Cited by 2 (0 self)
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: This lecture considers the optimisation of functional programming languages (particularly `lazy' languages) based on `strictness analysis'. Such optimisations alter evaluation order to allow more efficient translation into von Neumann architecture or to increase the parallelism in a sequentially specified system (such as that implied by lazysemantics) . Keywords: Functional languages, lazy evaluation, eager evaluation, strictness analysis, abstract interpretation. 1 Functional Languages The term `functional' as applied to programming languages has been used to apply to a number of related but different models of computation. As used here it will refer to purely functional languages, characterised by a complete lack of sideeffects and a very direct relationship with the calculus. This rules out languages such as ML and Lisp which, although emphasising the status of functions in the construction of programming and containing wellunderstood pure subsets, include forms of assignmen...
Fast Strictness Analysis Based on Demand Propagation
 ACM Transactions on Programming Languages and Systems
, 1995
"... Interpretation versus Demand Propagation Wadler [1987] uses abstract interpretation over a fourpoint domain for reasoning about strictness on lists. The four points correspond to undefined list (represented by value 0), infinite lists and lists with some tail undefined (value 1), lists with at lea ..."
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Interpretation versus Demand Propagation Wadler [1987] uses abstract interpretation over a fourpoint domain for reasoning about strictness on lists. The four points correspond to undefined list (represented by value 0), infinite lists and lists with some tail undefined (value 1), lists with at least one head undefined (value 2), and all lists (value 3). Burn's work [Burn 1987] on evaluation transformers also uses abstract interpretation on the abovementioned domain for strictness analysis. He defines four evaluators that correspond to the four points mentioned above in the sense that the ith evaluator will fail to produce an answer when given a list with the abstract value i \Gamma 1.
Semantic Analyses for Storage Management Optimizations in Functional Language Implementations
, 1991
"... One of the major overheads in implementing functional languages is the storage management overhead due to dynamic allocation and automatic reclamation of indefiniteextent storage. This dissertation investigates the problems of statically inferring lifetime information about dynamicallyallocated ob ..."
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One of the major overheads in implementing functional languages is the storage management overhead due to dynamic allocation and automatic reclamation of indefiniteextent storage. This dissertation investigates the problems of statically inferring lifetime information about dynamicallyallocated objects in higherorder polymorphic functional languages, both strict and nonstrict, and of applying that information to reduce the storage management overhead. We have developed a set of compiletime semantic analyses for a higherorder, monomorphic, strict functional language based on denotational semantics and abstract interpretation. They are 1) escape analysis, which provides information about the relative lifetimes of objects such as arguments and local objects defin...
Type Theory and Projections for Static Analysis
, 1995
"... A system of annotated types is proposed as a means of describing and inferring static information, such as strictness and constancy, about functional programs. An abstract semantics is given in terms of projections. A close connection between annotated type assignment and projection analysis is demo ..."
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A system of annotated types is proposed as a means of describing and inferring static information, such as strictness and constancy, about functional programs. An abstract semantics is given in terms of projections. A close connection between annotated type assignment and projection analysis is demonstrated.