Contracts and Specifications for Functional Logic Programming

Antoy, Sergio; Hanus, Michael

doi:10.1007/978-3-642-27694-1_4

Cited by 17 publications

(33 citation statements)

References 20 publications

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“…Our contracts are similar to the ones defined in [1], where the function specifications are written in the same language, i.e. Curry, so they are executable.…”

Section: Related Workmentioning

confidence: 99%

Runtime Verification in Erlang by Using Contracts

Fredlund

Mariño

Pérez

et al. 2019

Functional and Constraint Logic Programming

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During its lifetime, a program suffers several changes that seek to improve or to augment some parts of its functionality. However, these modifications usually also introduce errors that affect the alreadyworking code. There are several approaches and tools that help to spot and find the source of these errors. However, most of these errors could be avoided beforehand by using some of the knowledge that the programmers had when they were writing the code. This is the idea behind the design-by-contract approach, where users can define contracts that can be checked during runtime. In this paper, we apply the principles of this approach to Erlang, enabling, in this way, a runtime verification system in this language. We define two types of contracts. One of them can be used in any Erlang program, while the second type is intended to be used only in concurrent programs. We provide the details of the implementation of both types of contracts. Moreover, we provide an extensive explanation of each contract as well as examples of their usage. All the ideas presented in this paper have been implemented in a contract-based runtime verification system named EDBC. Its source code is available at GitHub as an open-source and free project.

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“…Our contracts are similar to the ones defined in [1], where the function specifications are written in the same language, i.e. Curry, so they are executable.…”

Section: Related Workmentioning

confidence: 99%

Runtime Verification in Erlang by Using Contracts

Fredlund

Mariño

Pérez

et al. 2019

Functional and Constraint Logic Programming

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“…The former is more laborious since an expression might evaluate to many partial values even if it has a single value. For instance, consider the list generator: The expression fromTo 1 5 evaluates to the single value [1,2,3,4,5]. According to the reduction relation defined in Sect.…”

Section: Refined Equivalence Criteriamentioning

confidence: 99%

“…Equivalence of operations was defined for functional logic programs in [5]. There, this notion is applied to relate specifications and implementations.…”

Section: Related Workmentioning

confidence: 99%

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Equivalence Checking of Non-deterministic Operations

Antoy

Hanus²

2018

Functional and Logic Programming

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Checking the semantic equivalence of operations is an important task in software development. For instance, regression testing is a routine task performed when software systems are developed and improved, and software package managers require the equivalence of operations in different versions of a package within the same major number version. A solid foundation is required to support a good automation of this process. It has been shown that the notion of equivalence is not obvious when non-deterministic features are present. In this paper, we discuss a general notion of equivalence in functional logic programs and develop a practical method to check it. Our method is integrated in a property-based testing tool which is used in a software package manager to check the semantic versioning of software packages. MotivationFunctional logic languages combine the most important features of functional and logic programming in a single language (see [4,20] for recent surveys). In this paper we consider Curry [24], a contemporary functional logic language that conceptually extends Haskell with common features of logic programming. Hence, a Curry function is evaluated lazily and may be non-deterministic when defined by overlapping rules. As discussed in [7], the combination of these features raises new issues for defining the equivalence of expressions. Actually, three different notions of equivalence can be distinguished:1. Ground equivalence: Two expressions are equivalent if they produce the same results when their variables are replaced by ground terms. 2. Computed-result equivalence: Two expressions are equivalent if they produce the same outcomes, i.e., variables in expressions are considered as free variables which might be instantiated during the evaluation process. 3. Contextual equivalence: Two expressions are equivalent if they produce the same outcomes in all possible contexts.⋆ This is an extended version of a paper appeared in → denotes the reflexive and transitive closure of this reduction relation. The equivalence of this rewrite relation and CRWL is shown in [28]. Equivalent OperationsAs discussed above, equivalence of operations can be defined in different ways. Ground equivalence and computed result equivalence only compare the values of applications. This is too weak since some operations have no finite values.Example 3. Consider the following operations that generate infinite lists of numbers: ints1 n = n : ints1 (n+1) ints2 n = n : ints2 (n+2)Lemma 2. Let x be an integer and rs and xs lists of integers such that x ≤ z for all z ∈ rs. Then, for some list of integers r, minRest x rs xs * → (m, r) with m ≤ z for all z ∈ (x : rs++xs) and perm (x : rs++xs) * → m : r (where rs++xs denotes the concatenation of the lists rs and xs).Proof. We assume that x ≤ z for all z ∈ rs. We prove the lemma by induction on the length of the list xs.Base case: xs = []:Since minRest x rs [] *

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“…Assertions have been considered in (constraint) logic programming, functional programming, and functional-logic programming (see (Mera et al 2009;Chitil 2011;Antoy and Hanus 2012) and references therein). However, we are not aware of any assertion-based, dynamic slicing system that is comparable to ABETS for either declarative or imperative languages.…”

Section: Conclusion and Related Workmentioning

confidence: 99%

Assertion-based analysis via slicing with`ABETS`(system description)

Alpuente

Frechina

Sapiña

et al. 2016

Theory and Practice of Logic Programming

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We present ABETS, an assertion-based, dynamic analyzer that helps diagnose errors in Maude programs. ABETS uses slicing to automatically create reduced versions of both a run's execution trace and executed program, reduced versions in which any information that is not relevant to the bug currently being diagnosed is removed. In addition, ABETS employs runtime assertion checking to automate the identification of bugs so that whenever an assertion is violated, the system automatically infers accurate slicing criteria from the failure. We summarize the main services provided by ABETS, which also include a novel assertion-based facility for program repair that generates suitable program fixes when a state invariant is violated. Finally, we provide an experimental evaluation that shows the performance and effectiveness of the system. This paper is under consideration for publication in TPLP.

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Contracts and Specifications for Functional Logic Programming

Cited by 17 publications

References 20 publications

Runtime Verification in Erlang by Using Contracts

Runtime Verification in Erlang by Using Contracts

Equivalence Checking of Non-deterministic Operations

Assertion-based analysis via slicing with`ABETS`(system description)

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Contracts and Specifications for Functional Logic Programming

Cited by 17 publications

References 20 publications

Runtime Verification in Erlang by Using Contracts

Runtime Verification in Erlang by Using Contracts

Equivalence Checking of Non-deterministic Operations

Assertion-based analysis via slicing withABETS(system description)

Contact Info

Product

Resources

About

Assertion-based analysis via slicing with`ABETS`(system description)