Programmation déclarative | EPFL Graph Search

vignette|Binario cropped. La programmation déclarative est un paradigme de programmation qui consiste à créer des applications sur la base de composants logiciels indépendants du contexte et ne comportant aucun état interne. Autrement dit, l'appel d'un de ces composants avec les mêmes arguments produit exactement le même résultat, quel que soit le moment et le contexte de l'appel. En programmation déclarative, on décrit le quoi, c'est-à-dire le problème. Par exemple, les pages HTML sont déclaratives car elles décrivent ce que contient une page (texte, titres, paragraphes) et non comment les afficher (positionnement, couleurs, polices de caractères…). Alors qu'en programmation impérative (par exemple, avec le C ou Java), on décrit le comment, c'est-à-dire la structure de contrôle correspondant à la solution. C'est une forme de programmation sans effets de bord, ayant généralement une correspondance avec la logique mathématique. Il existe plusieurs formes de programmation déclarative

Reactive Programming Abstractions for Complex Event Logic and Dynamic Data Dependencies

Ingo Maier

A large part of software written today is reactive. In contrast to batch mode systems, a reactive program continuously adapts itself to new input which often requires a substantial amount of engineering. Traditionally, reactive programs are implemented in terms of callbacks. This approach leads to an inversion of control, which makes it hard to reason about control- and data flow. A number of programming models have been proposed to improve on callbacks, most prominently constraint imperative programming (CIP) and functional reactive programming (FRP). Both approaches have their individual advantages and limitations. CIP often handles multi-way data flow well but some event handling logic is difficult to express and data flow sometimes difficult to predict. In FRP, data flow is predictable but restricted to a single direction. Complex event logic can become complicated and the programmer is sometimes forced to escape the functional programming model imposed by FRP. Existing CIP and FRP implementations do not support incremental changes. Declarative programming with time-varying data structures therefore quickly becomes inefficient. In this thesis, we propose a reactive programming model that is functional reactive at its core but allows the programmer to escape the functional reactive paradigm when necessary. It improves on previous FRP systems and also on CIP in a number of ways. Our implementation, Scala.React, supports all host language expressions without special adaptation. We provide an imperative data flow language that simplifies the processing of complex event patterns. A user of Scala.React can safely use callbacks or a variant of callbacks that reduces inversion of control if a more declarative solution is not obvious. Our reactive sequence data structure propagates incremental changes. It supports both first-order reactivity by means of composition similar to functional collections via map, filter, fold and alike, as well as higher-order reactivity with support for time-varying collection elements. Reactive lenses provide a way to declaratively program with multi-way reactive data flow that allows for local reasoning and is therefore predictable. All of these abstractions are implemented on top of a general propagation system that guarantees data consistency, supports atomic updates, and provides isolation of different reactive parts of a program. The core system is extensible and abstracts from the details of individual abstractions.

EPFL2013

Declarative Variables in Online Dating: A Mixed-Method Analysis of a Mimetic-Distinctive Mechanism

Daniel Gatica-Perez, Jessica Carolina Pidoux

Declarative variables of self-description have a long-standing tradition in matchmaking media. With the advent of online dating platforms and their brand positioning, the volume and semantics of variables vary greatly across apps. However, a variable landscape across multiple platforms, providing an in-depth understanding of the dating structure offered to users, has hitherto been absent in the literature. In this study, more than 300 declarative variables from 22 Anglophone and Francophone dating apps are examined. A mixed-method research design is used, combining hierarchical classification with an interview analysis of nine founders and developers in the industry. We present a new typology of variables in nine categories and a classification of dating apps, which highlights a double mimetic-distinctive mechanism in the variable definition and reflects the dating market. From the interviews, we extract three main factors concerning the economic and sociotechnical framework of coding practices, the actors’ personal experience, and the development methodologies including user traces that influence this mechanism. This work, which to our knowledge is the most extensive thus far on dating app declarative variables, provides a new perspective on the analysis of the intersection between developers and users of online dating, which is mediated through variables, among other components.

2021

Deprecating the Observer Pattern with Scala.React

Ingo Maier, Martin Odersky

Programming interactive systems by means of the observer pattern is hard and error-prone yet is still the implementation standard in many production environments. We show how to integrate different reactive programming abstractions into a single framework that help migrate from observer-based event handling logic to more declarative implementations. Our central API layer embeds an extensible higher-order data-flow DSL into our host language. This embedding is enabled by a continuation passing style transformation.

2012

Reactive Programming Abstractions for Complex Event Logic and Dynamic Data Dependencies

Ingo Maier

EPFL2013