The Web App Specification Language (Wasp) was recently released in alpha to help developers write modern web applications with less code. Just like Elm, Wasp is a domain-specific language written in Haskell. Unlike Elm, which only addresses single-page applications, Wasp also supports multi-page applications. The alpha release currently leverages a single web stack covering front-end and back-end (React/Node/Express/Prisma).
The Web App Specification Language self-describes as a programming language for building web apps with less code: Front-end, back-end and deployment – all within one concise DSL. The Wasp documentation explains.