Set functions for functional logic programming

Abstract

We propose a novel approach to encapsulate non-deterministic computations in functional logic programs. Our approach is based on set functions that return the set of all the results of a corresponding ordinary operation. A characteristic feature of our approach is the complete separation between a usually-non-deterministic operation and its possibly-non-deterministic arguments. This separation leads to the first provably order-independent approach to computing the set of values of non-deterministic expressions. The proof is provided within the framework of graph rewriting in constructorbased systems. We propose an abstract implementation of our approach and prove its independence of the order of evaluation. Our approach solves easily and naturally problems mishandled by current implementations of functional logic languages.

CHR(Curry): Interpretation and Compilation of Constraint Handling Rules in Curry

“…This combination allows better abstractions for application programming and has also led to new design patterns [1,5] as well as better abstractions in application programs such as implementing graphical user interfaces [12] or web frameworks [17]. The declarative multi-paradigm language Curry [11,18] is a modern functional logic language with advanced concepts for application programming [2,3].…”

“…The condition expresses the fact that primitive constraints are not allowed in the left-hand sides of CHR rules. 3 To denote simpagation rules, we introduce the operator "\\": In order to exploit the strong type system of the host language in CHR programs, we introduce user-defined CHR constraints as a data type. For instance, the CHR program of Example 1 contains rules for a single CHR constraint leq.…”

“…This combination allows better abstractions for application programming and has also led to new design patterns [1,5] as well as better abstractions in application programs such as implementing graphical user interfaces [12] or web frameworks [17]. The declarative multi-paradigm language Curry [11,18] is a modern functional logic language with advanced concepts for application programming [2,3].An important application area of declarative, and in particular, logic programming languages is constraint programming [19,22]. Since logic programming is a subset of functional logic programming, there exist various attempts to extend functional logic languages with constraint solving facilities (see [24] for a survey).…”

Compiling a Functional Logic Language: The Fair Scheme

“…4. In a LOIS system, the order of execution of disjoint steps of an expression does not affect the value(s) of the expression [3,12].…”

On the correctness of pull-tabbing

“…The set of all the parts of an object is computed by is built by'set, the implicitly defined set function (Antoy and Hanus 2009) of is built by. The simplicity of design and ease of coding offered by functional logic languages through non-determinism do not come for free.…”