Introduction to Programming in ATS

Commenters describe ATS as an intriguing, ML-inspired language with ambitions in systems programming and efficient compiled code. One commenter recalled taking the author’s compiler-design course and called it “an experience,” while another pointed to a talk introducing ATS systems programming. MLton and Felix also came up as related ML-inspired languages that optimize whole programs. A language designer said MLton had influenced their own work and ATS was a more complicated but valuable “north star”; they also suggested LLMs can help people discover less familiar languages when they know what to look for.

The main divide concerned ATS’s current state and accessibility. One commenter initially saw active development in ATS-Postiats, then acknowledged learning that a third version existed and complained that the project’s releases and direction were hard to track, arguing it needed broader community development. Others clarified that ATS2 is stable and usable but effectively frozen, with recent activity focused largely on build changes, while ATS3 (Xanadu) is the active effort and is not yet generally usable. They described ATS3’s two-layer type checking - ML-style types followed by dependent types - as an attempt to ease the learning curve. For following progress, commenters recommended the ATS users group and pointed to existing explanations of ATS2’s features.