This thesis examines trends in the academic and professional literature around immutable data and its relationship with declarative User Interfaces (UIs). Immutable data types are preferred by academic authors due to their increased safety, and commercial languages are increasing their support for them over time. More recently, declarative UIs are an exploding topic in industry, and these are related, although not as closely as one would expect. Declarative programming tries to focus on highlevel requirements, not low-level details. It is easier to do this if functions have no side effects, and immutable data is a guaranteed way of achieving this. To highlight this property, the declarative UI framework Flutter advertises “stateless widgets”, but their existence puts in highlights the lack of this property in most widgets. Consequently, we ask whether it is feasible to build a Graphical User Interface (GUI) toolkit using purely immutable data structures. To accomplish this objective, a purely immutable GUI toolkit is sketched and partially developed using Elm, a purely functional language in which all data structures are immutable. To understand the requirements of a GUI toolkit, we categorize and put in historical context, different design paradigms for UIs and relate them to core software-design principles. Leading toolkits allow developers to visualize and manage multiple views of their interfaces, including the view hierarchy, layout, interface to business logic, and focus management. By creating a concrete example, the research aims to provide insight into the limitations of utilizing purely immutable data within a GUI framework and suggests future work to mitigate these. / Thesis / Master of Science (MSc)

The rapid expansion of computer technology have forced several business sectors to integrate with the continuous development of techniques in order to assist them in various tasks. Many fields have happily embraced the technology implementing it in numerous ways, however the development speed have proven difficult to keep up with. The insurance industry have struggled with ridding themselves of old and monolithic legacy systems with a haphazard construction. These systems are costly, cumbersome and often reliant on a “third party” centered structure creating such flaws as data leaks and monopolisation. Blockchain is a distributed ledger operating over a peer-to-peer basis, with the intention to unshackle contemporary system from their dependence towards central authorities. Additionally, the peer-to-peer architecture introduced a new form of transparency which differs from contemporary solutions used in centralised systems, beyond the peer-to-peer architecture, the blockchain also incorporated consensus algorithms, allowing peers to verify one another to achieve consensus regarding the validity of each block. This resulted in a "trustless system" considering no single party in the community is dependent on the credibility of a central authority. In order for the blockchain technology to be applicable on the market it must overcome obstacles such as privacy and the new EU data protection regulation “General protection data regulation”. However a vague definition of personal data have caused ambiguity which appears to be irreconcilable with the blockchain technology. Research have therefore shifted its focus to explore opportunities for the technology to collaborate with techniques from centralisation in order to overcome its obstacles. / Datorteknologins hastiga expansion har bidragit till att mängder av olika yrkessektorer tvingats integrera teknologin i sin dagliga verksamhet för att bidra med vissa uppgifter. Då teknologin i stor utsträckning har varit till nytta har många yrkesgrupper välkomnat den, dock har teknikens utvecklingshastighet visats vara mycket hög vilket medfört viss problematik. Försäkringsbranschen har visats ha problem med att hantera vidareutvecklingen av sina gamla monolitiska “legacy” system då de är både utdaterade och konstruerade på ett ostrukturerat sätt. Dessa gamla system är kostsamma, svårhanterliga och baseras ofta på en systemarkitektur centrerad kring “tredje parter” detta medför problem som dataläckor och monopolisation. Blockkedjan är ett distribuerat journalsystem som struktureras med ett peer-to-peer nät som bas. Detta görs med förhoppningen att kunna frigöra existerande system från centrala autentiseringsparter. Dessutom har blockkedjan introducerat en ny sorts transparens som skiljer sig från de nuvarande centrala systemen. Blockkedjan inkluderar också consensus algoritmer som medför att alla deltagare kan verifiera varrandra och därmed nå ett uniformt beslut om blocks validitet. Dessa egenskaper resulterar i ett system som inte är beroende av att dess användare behöver lita på en centraliserad tredje part. För att blockkedjan ska vara användbar och framgångsrik på en öppen marknad finns vissa funktionskrav som måste uppfyllas. Ett av de främsta av dessa är EU förordningen “General protection data regulation”. Problem har uppstått då “General protection data regulation” innefattar vaga definitioner av “personlig data”, dessutom är de existerande tolkningar av konceptet svår applicerade för blockkedje tekniker. Detta har bidragit till att utvecklingen av rena blockkedje lösningar har stagnerat och utvecklingen dirigerats om till forskning inom hybrid teknologier som inkluderar tekniker från centraliserade system.