Rthat

Rthat is a fictional programming language used in academic and speculative contexts to illustrate ideas in reactive programming and type-safe functional design. In this imagined ecosystem, Rthat emphasizes predictable performance and the modeling of time-varying values. The name is not tied to any real acronym in official literature.

Origin and context: The term first appears in teaching prompts and speculative essays to explore design tradeoffs; there is no known production implementation.

Design goals and features: Rthat emphasizes referential transparency, immutability, and first-class signals to model time-varying values. It adopts lazy evaluation, supports algebraic data types and pattern matching, and includes a module system. Built-in support for event streams and backpressure enables composing reactive pipelines, and the syntax draws on influences from Haskell and OCaml for readability.

Usage and reception: In educational settings, Rthat is used to illustrate how language features interact in reactive programs and to discuss performance implications of stream processing. It is not implemented as a production language, though toy compilers or interpreters have appeared in some teaching materials.

Related topics include reactive programming, functional programming, and type systems. Since Rthat is fictional, it serves primarily as a tool for exploring design tradeoffs in language theory and pedagogy rather than as a reference implementation.