Lambda the Ultimate

Nick Benton and Neel Krishnaswami, ICFP'11, A Semantic Model for Graphical User Interfaces:

We give a denotational model for graphical user interface (GUI) programming using the Cartesian closed category of ultrametric spaces. [..] We capture the arbitrariness of user input [..] [by a nondeterminism] “powerspace” monad.

Algebras for the powerspace monad yield a model of intuitionistic linear logic, which we exploit in the definition of a mixed linear/non-linear domain-specific language for writing GUI programs. The non-linear part of the language is used for writing reactive stream-processing functions whilst the linear sublanguage naturally captures the generativity and usage constraints on the various linear objects in GUIs, such as the elements of a DOM or scene graph.

We have implemented this DSL as an extension to OCaml, and give examples demonstrating that programs in this style can be short and readable.

This is an application of their (more squiggly) LICS'11 submission, Ultrametric Semantics of Reactive Programs. In both these cases, I find appealing the fact the semantic model led to a type system and a language that was tricky to find.